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Commerce Raiding and Convoys

This article originally appeared in the February 2010 issue, and was reprinted in the November/December 2023 issue.

Commerce raiding is a big part of the general Traveller milieu and the OTU’s specific history. The cessation of interstellar commerce helped lead to the Long Night. The loss of interstellar shipping assets during the Rebellion was a major factor of the Hard Times and is still felt into the Viral Era. Commerce raiding played a role in the Terran Confederation’s victory in the Interstellar Wars. The Outworld Coalition fought the Third Frontier War primarily through raiding.

This emphasis naturally leads to some questions. In a broad sense, how does commerce raiding work? How can it be defended against? What are the effects raiding has on trade? Because I am in love with the sound of my own voice, I'll be addressing these questions after a * Mr Cameron previously used the handle “Larsen E. Whipsnade” as his byline.Whipsnadian* history lesson. We’ll examine the evolution of commerce raiding on Earth and then try and extend those lessons into Our Olde Game.

Commerce raiding predates navies. Always the favored tactic of ‘weaker’ navies, raiding, or the ‘guerre de course’, has never won a war in and of itself. It has substantially assisted nations in fighting wars however.

Commerce raiding is a strategic weapon, not a tactical or operational one. Raiding helps win battles through the diversion of assets and resources. If your opponent’s cavalry is off chasing the raiders you’ve dispatched to his rear, that cavalry will not meet you on the battlefield. Every ASW escort you force your opponent to build is one less offensive warship he can build. Every AA gun and crew you force him to deploy is one less AT gun and crew your tanks will face. Every cruiser he sends out to patrol the sea lanes is one less cruiser in his battleline when your fleets meet.

Threatening the commerce of your opponent forces him to protect it and allows you to ‘call the tune’, i.e., make him react to your actions. The more your opponent depends on seaborne commerce, the more you can make him dance to your tune.

During the American Civil War, the CSA never seriously threatened the Union closure of southern ports. Union forces maintaining patrols outside of southern ports did so with near impunity. CSS Virginia did have one glorious afternoon in March of 1862, but USS Monitor arrived that evening. The Union forces patrolling the coast from Chesapeake Bay to the Mexican border were never substantially threatened again.

The CSA’s navy did achieve one notable success however; its raiders chased Union merchant shipping from the world’s seas. Before 1861, the USA’s merchant fleet rivaled that of Great Britain’s in size and scope. By 1865, that same merchant fleet had ceased to exist. The CSA raiders did not sink all those hulls. Nervous owners and insurance underwriters simply flagged their vessels in other nations, primarily Britain.

The USN, straining in the early portions of the war to commission enough vessels to patrol outside of southern ports, was forced to dispatch warships worldwide in near futile attempts to protect merchant shipping and catch CSA raiders. The CSA raiders did divert a portion of the Union war effort away from the continental battlefields. Obviously, that portion was nowhere near enough to make a difference, but resources were diverted nonetheless.

This historical example shows us one of the first effects of commerce raiding; if seaborne commerce is a significant portion of your war economy, you must defend against raiding. Time, treasure, equipment, and blood are expended to combat raiding, usually in far greater amounts than the amounts put into raiding in the first place. As a defender, you want to win against the raider every time and in every place. As a raider, you need only succeed once in a while, just often enough to keep the threat fresh in your opponent’s mind.

Between 1865 and 1914, the changes in technology changed the nature of commerce raiding. Advances in both propulsion and communications worked against the raider.

Sailing ships had traversed the oceans along known routes, the winds they required forced them to do this. There were only a few ‘landfall’ points in any of the world’s oceans. A raider could loiter at these points and easily find his prey. Steam propulsion didn’t quite do away with these ‘gathering’ spots, but it did make them larger in area and thus harder to search.

Steam also fettered a raider to a fuel supply. During the American Civil War, CSA raiders could travel between landfalls under sail, only using their propulsion plants when actively raiding. Now that most merchant ships were also powered and faster, the raiders needed to use their engines all the time. Those engines required fuel and fuel became the Achilles’ heel of the raider.

Radio worked against the raiders too. Prior to wireless, a merchant could be taken or sunk and no news reach the world at large. Before, the operations of raiders in certain areas or along certain trade routes could only be determined by the failure of merchant vessels to arrive according to their, rather loose, schedules. More often than not, a raider’s presence was announced by the raider itself, arriving in port for supplies or to land prisoners.

Now, radio allowed merchants to regularly check in with port authorities over the length of their journey. Radio also allowed merchants to announce when they were under attack. The veil of secrecy raiders had operated under for millennia no longer existed. Raiders could no longer loiter along a trade route or near a landfall and scoop up merchants at their leisure. They had to strike quickly, take or sink their targets, and then leave the area as soon as possible.

Despite these handicaps, Imperial Germany’s surface commerce raiders did a superb job. They tied up Entente assets and resources in far greater proportion than their cost to the Kaiser. All were eventually hunted down and none really operated past the second half of 1917, but they made the Entente dance to Germany’s tune in places far from the Western Front.

One raider, Wolf, steamed along the seas the Entente controlled for over a year, taking and sinking many vessels, tying up dozens of warships, and causing all sorts of trouble, before returning safely home. Suspicion of her presence in the Indian Ocean actually delayed a troop convoy sailing from Australia to the Suez. British requests to the Japanese for help in hunting down Wolf gave Japan a stronger bargaining position at Versailles. She used that in turn to ask for and receive control of Germany’s Pacific territories, islands the USMC and USN would find themselves fighting across less than 30 years later.

As spectacular as the achievements of Kaiser Bill’s surface raiders were, they were not enough. The Central Powers were slowly starving under the distant blockade maintained by the Grand Fleet in Scapa Flow. The High Seas Fleet seemed unable, or unwilling, to break that blockade. Commerce raiding had made the Entente react, made them dance to Germany’s tune, but surface raiders would be horribly vulnerable around the British Isles. Something had to be done, something - anything - had to be tried, and something was. Slowly, hesitantly, in fits and starts, Germany worked out the next stage in commerce raiding. The submarine, a weapon originally designed to be used tactically in the role of coastal defense, was transformed into a strategic weapon.

Raiding forces your opponent to divert assets and resources to defensive purposes and away from using them against you. He must protect areas that you may or may not attack. Your opponent’s need to defend against your raiders everywhere means that you can force him to expend resources far out of proportion to the resources you devote to raiding. Thus, a numerically inferior force can use the threat posed by commerce raiding to divert forces away from themselves and lessen the odds they face.

Also, raiding mostly likely predates armies or navies. Bride stealing and organized looting are fixtures in human culture. Defending communities against raiders most certainly led to the creation of standing armed forces. While raiding on land was brutal from the start (the arson, rape, and pillage intendant with raiders are recorded for as far back as we have records), raiding at sea was almost gentlemanly in comparison. Part of that dichotomy can be laid at the romantic notion of us all being ‘sailors first and combatants second’ or ‘fighting the sea before fighting each other’. CSA commerce raiders may have destroyed the US whaling fleet in the north Pacific, but all the crews survived.

For most of our history, commerce raiding at sea involved little bloodshed when compared to raiding on land. Even self-proclaimed pirates spared their captives more often than not, although this may have been mostly for propaganda purposes. A commerce raider hailed its prey, sometimes with a show of force (such as the ‘shot across the bow’), and accepted the merchant’s surrender. Either a prize crew was sent aboard and the captured vessel sailed back to a friendly port or the vessel was sunk, usually through burning. In nearly all cases, the merchant vessel’s crew was either allowed to evacuate or were taken aboard the raider. All in all, commerce raiding at sea was a leisurely affair. Surrendering to a raider usually allowed you to eventually sail another day.

Technology changed all that and changed it for the worse.

Steam spread out a raider’s targets, made them much faster, and increased the chances that patrolling defenders could intervene. Radio allowed a raider’s victims to announce their capture to any who would listen, where before communication lag was a raider’s greatest asset.

Improvements in weaponry adversely affected raiders too. Quite deadly weapons could be secreted aboard innocuous vessels, Q-ships, which would then ‘surrender’ to raiders, coax them closer, and suddenly open fire. Far from friendly ports and constrained by their own resources, any damage a raider received could prove fatal.

Technology also forced surface raiders further and further into the geographical margins, away from heavily traveled sea lanes and away from busy ports. Those areas are defended and patrolled, something a raider cannot contend with. In the American Civil War, CSA raiders operated within sight of the US coastline. Other commerce raiders had captured ships right outside enemy ports. However, by 1914 only a madman would have tried to operate a surface raider in the Irish Sea as J.P. Jones had done in the American Revolution.

By the time of the Great War, technology had made surface raiders only a shadow of the threat they once had been. They could still tie up assets, force the enemy to divert men and materials into patrols and sweeps. However, unlike the CSA raider had done five decades earlier, they could no longer chase a nation’s entire merchant marine from the seas. Yet, commerce raiding as a method of strategic warfare had never been more attractive.

Thanks to industrialization, no nation could hope to maintain its economy, let alone fight a war, with only the resources within its borders. Every nation depended on commerce to sustain its war effort, all carried to a greater or lesser degree by seaborne vessels.

The Central Powers had risked a nitrate shortage until a process to fix nitrogen from the atmosphere was developed, literally at the last moment. Britain could not feed both her armies and populace without food from overseas and, to a lesser extent, none of the other combatants could feed themselves either. France, thanks to the stupidity of Plan 17, saw most of her deposits of iron ore occupied by Germany in 1914. She needed ore from overseas to make up the difference.

Geography allowed the Entente to put a distant blockade of Germany’s ports into effect from the earliest days of the war. Every loophole Germany tried; shipments through Holland, Scandinavia, the Balkans, Italy before she joined the Entente, every single one was found and stopped. The Kaiser’s armies were victorious in the East, occupied nearly all of Belgium and important pieces of France, yet Imperial Germany was still losing the war on a strategic level. The Entente need only hold fast and wait for the blockade to work. German needed a way to strike at her opponents strategically, to put the same pressures on the Entente that she was feeling.

Commerce raiding would be the method and the submarine, out of desperation, would be the tool.

Prior to the war, all the powers had built submarines with the same ‘noble’ motives in mind. They would defend coastlines and the littoral. They would attack warships and invasion fleets. They would carry on the war at sea in much the same manner it had always been carried on, gentlemanly and ‘we are all sailors first’. Those ideals completely ignored the realities of the submarine however.

Submarines were slow, painfully slow when submerged. They were delicate. Even minor damage could sink one or prevent one from diving. Compared to other weapons, their torpedoes were slow and had a very short range. Guns routinely threw shells at supersonic speeds over 10 miles, torpedoes were lucky to travel a third of that at a speed measured in tens of knots.

Given their nature, submarines were trappers, not chasers. They could not detect an opposing vessel at any great distance, run it down, and sink it. They had to lay in wait, hoping the target would come to them. Submarines had ‘glass jaws’ too. They couldn’t slug it out with their opponents. They had to strike from ambush, hoping to disable the enemy before the enemy even knew they were there.

Despite the ‘warship sinking only’ intentions of all the powers building submarines, those vessels were made to order for commerce raiding. Indeed, given the their inherent weaknesses, merchant shipping was the only target submarines could attack with any hope for regular success.

British propaganda aside, Imperial Germany didn’t issue a blanket ‘sink on sight’ order to their submarine force from Day One of the war. They announced successive blockade zones, pledged only Entente flagged vessels would be sunk, even tried to follow the ‘cruiser rule’ of warning vessels prior to sinking them. All these hesitant steps proved themselves to be useless and, in some cases, suicidal for the submarines involved. Surfacing and announcing your intention to attack only allowed the fragile submarine to be counterattacked. Giving merchant crews time to evacuate gave opposing warships more time to intercept you. Attempting to determine the nationality of a target before firing simply let the target steam away from you.

By fits and starts and seemingly without any coherent plan, Imperial Germany invented ‘sink on sight’ submarine warfare and nearly brought Britain to her knees. Driven to desperation, Britain was ready to try anything and everything. The wild and weird ideas thrown at the submarine ‘menace’ are beyond the scope of this essay, but none worked well enough to stop Germany’s submarine commerce raiding campaign. The RN was eventually all but forced to resurrect the idea of convoying. That did the trick. Convoying worked, but not for the reasons most people think it worked.

To say ASW was primitive during the Great War is to be kind. ASDIC was little better than putting your head underwater and listening. Depth charges had as good a chance of sinking the vessel dropping them as they did of sinking their target. Aircraft had very limited loiter times and could not carry weapons that were large enough to do much good. Most ASW sweeps consisted of every man not on watch standing topside and looking for periscopes.

Convoys worked because they limited a submarine’s chances of stumbling across a merchantman and not because the convoy’s escorts blasted any and all submarines that got near. Before convoying was instituted, merchants steamed in and out of port constantly either alone or in small groups. This ever present flow of targets enabled the slow submarine to sooner or later find itself in a good firing position. It didn’t matter if one merchantman steamed past on a poor attack bearing, another would soon be along. By controlling the number of arrivals and departures, convoys limited the number of chances submarines had to attack.

Convoys also made it possible for foreign flagged vessels to feel safe steaming into the war zone again. The submarines hadn’t done their work only by sinking vessels, they’d also done it by preventing vessels from sailing in the first place. For every ship the submarines sank, many others simply avoided sailing to Britain and France at all. It doesn't matter whether a vessel is sunk or its owners won’t allow it to travel in a war zone, in neither case can that vessel be used carry the cargos you need. By assuaging the fears of the neutral vessels, convoys increased the amount of shipping steaming for the Entente.

Convoys were a double-edged sword however. By limiting the number of departures, you limit the amount of tonnage delivered. This wouldn’t be too much of a problem in the First World War; it would become a problem in the Second, though.

The return of convoying allowed the Entente to survive Germany’s most serious attempt at a strategic offensive. Attacks on merchant shipping was nothing new, commerce raiding has been with us a long time, but using submarines for those attacks was new. The Entente survived Germany’s attempt to blockade them, but the Central Powers did not survive the blockade the Entente had maintained since 1914. Although the cease fire was signed on 11 November 1918, it should not be forgotten that the Entente blockade of Germany was kept in place until late 1919 when the Central Powers had signed the various treaties ending the war.

One of the participants at Versailles remarked that the treaty wasn’t a peace treaty but merely a twenty year cease fire. An oddly and sadly prophetic turn of phrase.

Commerce raiding in the next war would prove to be much more effective, nearly winning a war for one combatant and not the combatant that you think!

The main points I attempted to bring across in the previous paragraphs were:

  1. Defense against commerce raiding diverts more assets and resources than the raiding itself requires.
  2. Forcing an opponent to divert those assets and resources can help balance the force ratio you face.
  3. If your opponent requires commerce for basic economic reasons, commerce raiding can cripple his ability to support a war.
  4. Commerce raiding works by more than just destroying vessels. Convoys naturally limit the tonnage moved and the threat of destruction prevents some vessels from travelling altogether.

The arrival of the submarine in WW1 began a new phase in commerce raiding. The nature of submarines, the technologies that made them possible, forced them to be used in only certain ways. Unlike in previous centuries, merchant vessels were now sunk in ambush, without warning. Their crews were no longer allowed time to evacuate their ships and could no longer be brought aboard the raider that had sunk them. Commerce raiding at sea now became as bloody as it had always been on land.

The crude nature of WW1 submarines was matched by the crude nature of the weapons used against them. Convoying worked in WW1 because it lowered the chances that a submarine could intercept a merchant vessel and not because the convoy’s escorts were able to drive the submarines off.

During the twenty year cease fire period between the two World Wars, several powers looked to the Kaiser’s U-boat arm and learned very different lessons. The US and Japan built large submarines with the vast Pacific in mind. Japan, despite all indications that submarines could rarely inflict significant losses on naval assets, stressed anti-warship operations. The US, perhaps disingenuously, stated their boats were for sinking warships too. The US fleet boats would become nearly perfect commerce raiders however.

Britain built submarines for both commerce raiding and ASW roles. So did the Italians. Germany, despite being forbidden submarines by Versailles, built and operated boats in Holland and Finland in much the same way their army and air force tested designs and tried out doctrines in the Soviet Union. (All of these secret building and test programs in foreign countries began before the Nazis came to power.)

Even more oddly and despite the ‘lessons’ from the Kaiser’s War, Germany entered WW2 with fewer submarines on hand than it had when WW1 started. Those submarines began commerce raiding operations almost immediately however. While the real assault on Britain’s seaborne commerce had to await the fall of France and the construction of more submarines, it became apparent that the march of technology and advances in doctrine had improved the submarine far more than it had improved her opponents.

German submarines were now faster, both on the surface and beneath the waves. Their torpedoes, while still buggy, were far better than those the Kaiser’s U-boats had used. More importantly, they used very different tactics; attacking at night on the surface like PT boats and only submerging to escape. During the time it took the Allies to develop and deploy the material, technologies, and doctrines required to defeat them, the U-boats racked up spectacular tonnage totals. Yet they never came close to severing the Atlantic lifeline.

Let me repeat that, despite both Nazi and Allied propaganda, the U-boat never, ever came close to shutting the Atlantic to Allied shipping. Between 1939 and 1945, 99.4% of merchant vessels crossing the North Atlantic made port safely. That safe transit rate stayed pretty much steady, varying by at most a percentage point or two throughout the entire course of the war. Even during the best years the U-boats had, roughly between mid 1940 and mid 1943, well over 95% of merchant shipping in the North Atlantic reached port safely. So what was all the shouting about?

First, the huge number of safe transits are due to efforts the Allies put into countering Germany’s commerce raiding efforts. Thanks to WW1, the Allies took the submarine threat seriously from the very beginning and devoted considerable effort towards countering that threat. The Allies eventually had far more many vessels engaged in purely ASW efforts than entire number of U-boats the Kriegsmarine launched. The number of Allied aircraft tasked with ASW and convoy protection nearly equaled that of the entire Luftwaffe at its height.

Second, even an unopposed convoy system means there will be a shortfall in the necessary shipping tonnage. By restricting the sailing of vessels until such time as they can be formed into convoys and by restricting the sailing of those convoys until you feel they can be properly escorted, you limit the flexibility of your merchant marine. When viewed exclusively from a scheduling standpoint, convoys are extremely inefficient.

Third, a war economy requires much more shipping than a peacetime economy. Odd and additional resources are needed for essential industries, armies and fleets must be supplied over great distances, and the attrition of material means that everything needs to be built many times over. Simply going to war puts a merchant marine under strain and locking vessels into a convoy system limits their scheduling efficiency. Both of those factors can place a merchant marine and a nation’s seaborne supply routes in a very precarious position, a position which commerce raiding can exploit.

That is what the Kriegsmarine’s U-boat arm exploited. The everyday requirements of war had already stretched Allied shipping too thin. By threatening to upset that delicate logistical equation, the U-boats forced the Allies to expend far more effort, in the form of men and materials, then the price Germany paid for deploying the U-boats in the first place. The scales were so finely balanced that, each time the Germans placed the tiniest of pressures on them, the Allies were forced to respond with a far greater pressure of their own.

As good a strategic weapon as the U-boats were however, Germany did make two major mistakes. They utterly failed to keep up with the Allies in the technology race and they failed to concentrate the U-boat against weak links in the Allied supply chain.

In this manner, the U-boat campaign resembled the Allied strategic bombing campaign. Neither campaign every seriously threatened the opposing side, but both campaigns had to be countered at a great cost.

In the Pacific theater of the same war, two very different submarine campaigns took place: one abysmal failure and one spectacular success.

The IJN had large, well-designed submarines, some with their own scout planes, the best torpedoes in the world, motivated personnel, and the absolute worst submarine doctrine of any of the combatants. Completely ignoring the past inability of submarines to regularly and successfully engage naval targets, the IJN submarine arm was fixated on attacking Allied warships.

Because of this, submarines contributed very little to Japan’s war efforts. With very few exceptions, the Allies were able to ignore IJN submarines from a commerce raiding standpoint. Merchant shipping routinely sailed between the US West Coast, Hawaii, and ports even further west unattended. IJN submarines made cruises to the busy US West Coast throughout the war, only to monotonously record ‘no contacts’(!!!) in their patrol logs.

Once again as shown in the First World War, attempts to use submarines as anything but commerce raiders achieved, at best, spotty results. Although deployed in picket lines, the IJN boats failed to spot the US carriers deploying to Midway, failed to spot or prevent any of the innumerable US landings across the Pacific, and failed to substantially interfere with any US naval operations. (To be fair, the US boats didn&Rsquo;t do too much better in those roles.)

Shackled by faulty operational doctrine, Japanese submarines spent most of the war on fruitless patrols, acting as cargo vessels for isolated garrisons, or mother ships for various suicide missions. They contributed very little to the Japanese war effort and thus allowed the US to contain them with a relatively small effort. The US ASW measures in the Pacific actually grew lax as the war went on, as illustrated by the loss of Indianapolis.

As Japan’s opponents, the US at the beginning of the war had some of the world’s best submarines, definitely the world’s worst torpedoes, and a confused operational doctrine. Problems with torpedoes and doctrine lasted until early 1943, after that the US submarine force was unleased on Japanese merchant traffic with an unholy vengance.

The US submarines shared same good fortune their German counterparts did. Japan, like Britain, required seaborne imports to keep her war economy functioning and that commerce could be targeted in a strategic sense. But the US also enjoyed many benefits the Germans never dreamed of.

German U-boats had to transit cchoke points the North Sea, Bay of Biscay, Sea of Norway, etc., in order to reach their operational areas. US boats had the vastness of entire western Pacific to patrol. Chokepoints in the Pacific merely concentrated merchant vessels as targets. Chokepoints in the Atlantic concentrated U-boats as targets. US boats were built and operated from relative safety while German yards and submarine pens were the subject of air raids.

The US also eventually enjoyed a better operational doctrine than their German counterparts. For the Germans, a ship sunk was a ship sunk. Type, location, cargo aboard, none of that mattered. To the Germans, a tramp loaded with bananas off Sierra Leone was just as good as a tanker loaded with avgas off Liverpool. The US, thanks in part to code breaks, went after the critical cargoes Japan needed, primarily oil, rubber, and tin.

US submarines and their equipment were the recipients of constant technological improvement. Starting in 1943, US boats deployed with their own radar sets, something the U-boats never had despite Germany’s lead in radar development in the 1930s. US boats used HF-DF another technology the U-boats never enjoyed. Advances in cryptography on the Allied side allowed US boats to be steered towards targets.

Technology greatly assisted the enemies of submarines too. In WW1, aircraft accounted for one confirmed submarine kill. In WW2 in the Atlantic alone, aircraft sank slightly over 200 U-boats and assisted in the destruction of dozens more. Advances in aircraft, weapons, radar, HF-DF, and cryptography helped you hunt down submarines, but only if you made the effort to develop them in the first place. Germany’s commerce raiders and Japan’s commerce defenders fell further and further in the technology race while the Allied raiders and defenders opposing them set the pace.

Most importantly, Germany’s opponents recognized and dealt with the threat poised by commerce raiding. They devoted men and materials to the problem, allocating resources not just to fight the undersea raiders but to destroy them. The Japanese never did this, despite being the combatant most reliant on seaborne imports.

Britain began convoying merchant traffic when the war began, not all merchant traffic, but a healthy percentage of it. Japan, while convoying military formations, didn’t truly begin merchant convoys until 1944. Britain and the US built convoy escorts by the hundreds and had aircraft tasked to the ASW mission numbering in the thousands. Japan did not, indeed could not, make the same effort.

The Western Allies also devoted resources to ensuring that amount of shipping available to them during the war grew. Again Japan could not do this and Japan never even planned to do this. Between 1942 and 1945, Imperial Japan launched approximately 3.3 million tons of merchant shipping. In 1943 alone, the US launched 11.5 million tons of merchant shipping. Despite the U-boats’ record tonnage numbers, the Allies had more merchant ships at the end of 1942 then they had at the beginning of 1942, and the same can be said for the rest of the war. Japan, on the other hand, had fewer merchant ships at the end of 1943 than at the beginning and those numbers continued to drop despite the 3.3 million tons of shipping she launched.

During the war, Japan did not defend against commerce raiding allowing US forces to savage her merchant marine and deny her critical resources. During the war, Japan did not engage in commerce raiding, allowing the US to direct critical resources into other efforts. By ignoring the strategic warfare benefits of commerce raiding, Japan made far easier her eventual defeat.

By 1945, the biggest problem US submarines faced on patrol was a dearth of targets. The US boats reverted to the methods their 19th century commerce raiding counterparts would have recognized; stop, search, seizure, and sinking of suspect vessels at sea. What was left of Japan’s seaborne commerce was now carried on coastal sampans. Not wanting to waste torpedoes on such small targets, US submarines would approach those tiny vessels on the surface, order the crew to abandon ship, and sink their target with deck guns, satchel charges, and hand grenades.

When we compare and contrast these three submarine campaigns, we see that, from a strategic warfare standpoint, the US and German campaigns were successful and the Japanese campaign was a dismal failure.

The German campaign was successful because it diverted their opponents’ resources. The Western Allies were forced to expend many more resources on a commerce raiding defense than the Germans spent on mounting a commerce raiding campaign. The Germans did not ‘cut’ any supply lines, they never even came close to ‘cutting’ any supply lines, but they did force their enemies to expend supplies in areas where they did not wish to.

The US campaign was successful because it denied their opponent supplies. In this the US commerce raiding campaign was atypical. Only in very rare circumstances do commerce raiding campaigns ‘cut’ the lines of commerce. In the US case, it was a mixture of their technological superiority and their opponent’s blind spots that allowed this unprecedented success.

The Japanese campaign was a failure because it never occurred at all! The IJN should have instituted a submarine commerce raiding campaign but did not. Also, the Japanese should have defended themselves against such a campaign but, again, did not. With these two failures, the Japanese were denied resources they desperately needed and could not force their enemy to expend his own resources on defense. That acted as a “double whammy”, the Japanese saw their own resources wane and allowed their opponent’s to wax for the very same reason.

So what can we learn from historical commerce raiding that can applied to the fictional commerce raiding in the Traveller Universe? I think history provides us with the following lessons:

  1. Commerce raiding is both a useful and important aspect of strategic warfare.
  2. Whether you engage in commerce raiding or not, you must still actively defend against it.
  3. While any amount of commerce raiding can help in a strategic sense, a well thought out and well supported campaign can reap huge dividends for your war effort.

Please note, none of these suppositions require any specific technologies. They will work with TL9 missile-armed STL boats, TL 15 PAW-armed jump raiders, and TL 2 catapult-armed triremes.

An important aspect of commerce raiding in Our Olde Game will be the ‘jump geography’ of that setting. By the term ‘jump geography’, I am not referring to mains and clusters or jump drive parsec ratings by TL. Rather, I’m referring to the nature of jump itself; jump limits, jump masking, and jump accuracy, both distance and temporal.

Just as the geography of Earth assisted or constrained the commerce raiding campaigns of the past, the ‘jump geography’ of the Traveller setting will assist and constrain the commerce raiding campaigns of our fictional future.

We have examined history and found that, while commerce raiding rarely, if ever, actually won wars, it did provide a substantial strategic benefit for those who practiced it. Commerce raiding delivered this benefit by forcing your opponent to divert resources into commerce defense and away from his offensive war effort, all at a relatively small cost to you.

What”s more, the primary defense against commerce raiding, the convoying of merchant vessels, also worked in the raider’s favor. While convoys made it harder for raiders to intercept and sink merchant traffic, they also limited the flexibility of the convoying power’s shipping schedules. This inflexibility in turn creates an artificial shipping shortage adding to the shortage actual raiding creates.

Commerce raiding interferes with your opponent’s shipping capacity by three methods. First, it actually destroys or damages vessels. Second, it forces an enemy to convoy his vessels limiting the number of times they can travel. Finally, vessels are prevented from travelling at all, due to a fear for their destruction.

All of this is fine, but it can it really be transported from historical Earth to our fictional Traveller universe? Commerce raiding works on Earth because no industrial nation can meet all of its needs without imports. Would the same be true in the 57th century? I believe the answer is a qualified ‘yes’.

Canon has the collapse of trade leading to the collapse of interstellar civilization and the death of worlds. Whatever it is that merchants move between worlds, unobtanium or uberwidgets, the lack of that traffic adversely effects worlds, sometimes to great extremes. High pop, high tech systems may be - should be - largely immune to the effects of a loss of trade, but canon has these worlds suffering also. Whatever it is that interstellar commerce provides the worlds of the future, it is as vital to them as international trade is to us.

Canon also has combatants in many times and many places engaging in commerce raiding. The Terran Confederation raids the Ziru Sirka. The Outworld Coalition raided the Marches during each of the Frontier Wars. During the Third Frontier War, the Coalition did little but engage in commerce raiding. The Julian Protectorate forced a stalemate with a young Third Imperium thanks in no small part to aggressive and widespread commerce raiding. The Vargr need only be mentioned in passing, raiding is that species’ preferred method of war.

The list of commerce raiding powers in Traveller canonical history is lengthy. Commerce raiding takes place in Traveller. It is as least as effective as it has been on Earth. The question before us now is how does that raiding take place? And, more importantly, how is it defended against? An examination of the ‘geography’ in which this far future commerce raiding campaign will be fought should help us.

Interstellar commerce will be traveling between stellar systems, naturally. In the Traveller Universe, this requires the use of jump drive and nature of jump drive lays out the ‘geography’ of our battlefield.

For most of our convoy’s voyage, jump space is the defenders’ best friend. Jump space is safe space. The enemy cannot engage our convoy while it is in jump space. Just as the seagoing convoys on Earth looked forward to foul weather, shallow water, and friendly coastlines, the convoys of the 57th Century will yearn for jump space.

Vessels entering jump must do so beyond 100D of a +1km object. (Yes, I know it can be done at +10D, but with a greater risk of misjumps. We’re shipping critical cargoes here, do you want to throw a steady percentage of it away in misjumps?) Normal space is the only space where commerce raiding can occur and cargo vessels will only be traversing a relatively small part of it. Once again, this works in the favor of the defenders, a 100D ‘bubble’ can be swept constantly and defended. Enemy raiders would be forced to operate in or near this bubble to damage or destroy any cargo vessels.

With cargo vessels spending most of their time in jump space and only a ‘short’ period of time in normal space dashing to the 100D jump limit, the job of commerce raiders begins to look nearly impossible. There are other factors that put the scales back in balance however.

Jump masking and jump shadows will work in the raiders’ favor. Any object that exerts a 100D jump limit also masks travel through jump space. A vessel’s plotted course must clear the jump limits of all the objects between the jump entry and exit points.

Stars create the largest jump masks and shadows. In the case of the Sol System, Earth orbits relatively close to Sol’s 100D jump limit. On occasion, vessels departing Earth for other systems have to clear Sol’s jump shadow, a ‘bubble’ with a radius of about one AU.

Convoys avoiding jump masks and shadows will spend a longer amount of time in normal space. This in turn will allow raiders more opportunities to engage them.

The conservation of momentum in jump space and stellar velocities will help the raiders. A vessel retains the same vector upon exiting jump space that it did when it entered jump space. This, coupled with differing stellar velocities, means that merchant vessels will rarely thrust directly for the jump limit and enter jump. They will have to choose a narrow set of vectors to bring with them through jump. If establishing those vectors causes them to spend more time in normal space, the raiders will have more time to act.

The length of a convoy’s entire voyage will assist the raiders too. Only a few voyages will be one jump in length, most will require several jumps. The intermediate systems along a convoy’s path may be weakly defended or not defended at all. Each ‘stop’ along a multi-jump convoy route will give the raiders a chance to operate.

Refueling requirements will also assist the raiders. Cargo vessels and escorts must be refueled after jump. Fueling can take place at ports, gas giants, ice bodies, any number of locations, but ports will be the safest. Wilderness refueling takes time, time that any raider can put to good use.

Raiders are helped yet again by the fact that they needn’t destroy merchant vessels, they only need to damage them. A hit to a power plant or drive, a computer, any vital component in a system that can’t perform the necessary repairs strands the merchant vessel. Once damage causes a vessel to drop below the convoy minimum, say 1G and Jump 2, that vessel must be left behind for the good of the rest. The cargo it carries might as well be lost.

Let’s examine a few potential convoy routes. Each route assumes a convoy with a jump capability of two parsecs. (Jump2 was selected in order to cut down on the ‘length’ of the routes and because GT:FT makes a good case for the majority of Imperial cargo traffic to travel at Jump 2).

Our first convoy travels between Porozlo/Rylanor and Regina/Regina. The convoy route passes through Gileden/Rhylanor, Echiste/Lanth, Rech/Lanth, and then either Dinomn/Lanth or Yori/Regina before reaching Rhylanor. Five jumps in all, perhaps two months travel time when you take refueling into consideration. This route, while the ‘fastest’, may not exactly be the ‘best’, especially when you consider the systems the convoy will be passing through.

The first refueling stop on our route is Gileden. That system has a class C port, a TTL of 6, and a pop level of 1. Any defenses there are definitely deployed from another system. Porozlo, with a pop level of A (10), may picket or defend the two parsec distant Gileden system in the same manner and for the same reason that the Western Allies occupied and defended Iceland during WW1.

The next convoy stop would be Echiste, class C port again, a TTL of A, and a pop level of 3. Again, Echiste would be unable to defend itself, let alone assist in defending a convoy. The convoy’s escorts and, hopefully, occasional sweeps by other Imperial forces would be needed to keep the convoy’s Echiste lay-over safe.

Rech, our convoy’s next stop, has a class D port, a TTL of 6, but a pop level of 7. Given off-world equipment, Rech’s system defenders and COACC may be able to keep convoys safe on their own.

After Rech, our convoy can choose between two routes, through Yori or through Dinomn. With a class B port, Dinomn would be able to refuel our convoy faster than Yori’s class C. However, Yori does boast a slightly higher TTL, an A vs. Dinomn’s 9. Yori also has a larger population than Dinomn, pop level 7 vs pop level 6. The choice of routes isn’t clear here; the convoy could just as well choose either. Route selection would most likely be determined by additional factors: levels of raider activity, location of friendly forces, and so forth.

Finally, from either Yori or Dinomn, our convoy reaches the relative safety of Regina.

The second convoy route, between Regina/Regina and Efate/Regina, passes through intermediate systems even less capable then those between Porozlo and Regina. Whange and Forboln both have class E ports, low TTLs, 7 and 4 respectively, and low pop levels, 1 and 6 respectively. Yet, this convoy route is actually better than the first one. Force based in Efate and Regina can each patrol the single system on their sides of the convoy route. A convoy passing between Regina and Efate could have significant naval forces shielding it without any difficulty.

Our two convoy routes point out some interesting concepts. The second route passes through systems ill suited to support such traffic, but is easy to defend. The first route, a ‘least time’ route over a longer distance than the first, may not be the best choice for convoys between Porozlo and Regina. Another route could pass through intermediate systems more suited for defending the convoy, call it ‘defensive island hopping’, but that take a longer amount of time. Selections between routes will depend on a whole host of factors like time, defenses, and the known or suspected presence of the enemy. The ‘answer’ to these questions will always vary from convoy to convoy.

Convoy life and escort duty will be no walk in the recreation dome. Keeping a convoy of cargo ships in any sort of order will be more like herding cats than directing a marching band. We are dealing with people, first and foremost. There will be the grizzled old free trader captain who thinks the navy commander is snot nosed infant and there will be the naval officer who think all merchant spacers are oxygen thieves. There will be those vessels that, either through happenstance or incompetence, ignore or fail to carry out an order.

Normal space maneuvering will be a nightmare, even with the help of computers. Wildly different vessels, with even wilder crews, will all need to achieve the same vector, all usually at just one gee, the acceleration available to the slowest.

They’ll need to reach the calculated jump point in a very narrow time window. If MT”s squadron rules are used, and I firmly believe they should be, the jump plot of ever vessel in the convoy and among all the escorts will need to be shared and calibrated against one another.

Upon exiting jump space, all the convoy”s vessels may arrive within minutes of one another thanks to MT’s squadron jump rules, but they will still be scattered about; jump distance accuracy is 3000km per parsec jumped. The convoy will have to take time to redraw its defensive formation from vessels scattered across 6000 or more kilometers.

Refueling after every jump will take time. I seriously doubt that a convoy will attempt wilderness refueling unless there is no other choice. Skimming a gas giant is already dangerous enough without having the possibility of raiders engaging you. Cracking fuel out of planetary oceans or ice takes precious time too. Every minute spent in normal space is a minute that raiders can get to you. The longer you travel in-system, the longer it takes you to refuel, the more danger you are exposed to.

The nuts and bolts of defending a convoy from strikes by commerce raiders is a little hazy in canon. There seems to be no specific 57th Century version of an ‘area defense’ or ‘AA’ ship. Escorts cannot place themselves between their charges and harms’ way. In LLB2 and Mayday, vessels can fire at any targets that may be in range. IIRC, MT and TNE’s BL have similar mechanisms.

HG2 allows vessels to ‘screen’ other vessels from enemy attack through a ‘line&rsquop; and ‘reserve’ mechanism. Once the vessels in the ‘line’ are reduced to having no offensive weapons left, the reserve may be attacked. This is the only mechanism in Traveller that I am aware of, that would allow escorts to shield their charges.

There will never be enough escorts. The demands of the fighting fronts will continually suck combatants into the ‘real’ action and away from the convoys. Some escorts will travel with the convoys, attempting to shield or defend the merchants from any attack. Others will travel ahead of the convoys by hours or days, trying to ‘sanitize’ the route being used. Still more, if they are available, will patrol at random hoping to stumble across any raiders before they can strike.

Raiders will employ a number of different tactics and designs. At first glance, missiles seem to be the preferred raider weapon. Launching a few volleys at a distance allows the raider to choose the range of engagement and increase the chances that he will be able to avoid any damage inflicted by the escorts. Missiles mean resupply though. A missile-armed raider will eventually have to return to base or rendezvous with supply ship or pre-positioned caches.

Raiders with energy weapons can ignore supply issues for far longer then their missile armed brothers. Using beams means closing on your targets however and that means you’ll run a greater risk of being damaged by the escorts or by the merchant vessels themselves.

In both cases, the raiders will be attempting to damage vessels, not destroy them. A long series of attacks that cause minor damage to many enemy vessels and no damage to yourself is preferable to a single attack that destroys a few enemy vessels but forces you to return home for repairs.

Specific tactics will depend on weapon choices, the number of vessels available, even tech levels, but raiders will annoy more than they attack. Simply showing themselves and forcing resources to be diverted to defend against the possibility of their attack is a victory. ‘Bait and switch’ operations may be used; some raiders allow themselves to be run off by patrols sweeping ahead of the convoy, while others lay doggo and wait. One raider coaxing or stooging an escort away from the convoy could allow free fields of fire for others.

The operational possibilities for both sides are endless; A begets B which in turn begets C and so on. Each side will need to remain flexible, ready to change tactics, schedules, doctrine, everything in response to the other's changes. The initiative will swing back and forth between both sides during the whole course of the campaign.

Commerce raiding is strategic warfare. No flashy, and costly, successes are required. The watchwords are ‘attrition’ and ‘diversion’. Discomfort your enemy, make him dance to your tune, make him expend far more effort defending himself from your attacks then the effort you expend in making them.

Finally, leaving aside the great strategic benefits of commerce raiding and the sheer necessity of commerce defense, raiding and convoying are made to order for the role-playing portion of Our Olde Game. In a commerce raiding/defending campaign, the PCs can count. Their vessel, their job, isn’t lost in the numbers. They aren’t one of ten thousand marines serving in a battle fleet. They aren’t just another engineer among hundreds aboard a dreadnought. They are the battery chief trying desperately to slag that raider before it can hit the merchies. They are the comm tech trying to coax dozens of free traders into some sort of order. They are the raider captain trying to outguess her opponents and discern where their convoys will try and refuel next.

Thus ends my dissertation. I hope you enjoyed reading it, and that all this helps your games somehow. I hope you’ll tell me where I got it completely wrong. Most importantly, I hope you all have FUN. Remember, YTU, MTU, the OTU, it is all Traveller and it is all good!