Disguised as neutral-nation freighters but packing a hidden punch, Germany’s merchant raiders bedeviled the Royal Navy during both world wars.

Sophisticated carrier-based airplanes certainly shifted the odds in the 1940s, but as World War II loomed in the mid- to late ’30s, combatant navies had to decide how they’d wage war based largely on their guns and tons. The enormous Royal Navy was able to range freely from its British Isles bases and was so heavily tubed that it feared no rival—Germany, obviously—in any turret-to-turret confrontation. The Kriegsmarine had to fight a sea battle simply to sail from its homeports through the constricted and easily interdicted Baltic and North Sea channels, like a rottweiler chained to its doghouse. So the British were happy to go at it fleet to fleet, despite the horrendous loss of the battleship Hood in the Denmark Strait confrontation with Bismarck—more an embarrassment than a refutation of British strategy.

The Germans, however, had been constrained by the Treaty of Versailles from developing a meaningful capital ship fleet during the interwar period. They came up with a day-late-dollar-short collection of pocket battleships and heavy cruisers that had either big guns and less armor or lighter guns and more speed. Consequently, Bismarck, Tirpitz, Scharnhorst, Prinz Eugen, Graf Spee and Admiral Hipper were never prepared to fight a heavyweight title match.

So the German navy elected to avoid fleet confrontations and instead attack Britain’s maritime trade channels. U-boats were the primary weapon, as shipyards could crank them out by the dozens. But their range was limited. Largely restricted to the North Atlantic, they had to return frequently to bases in Europe to refuel and rearm. (Ideally, they’d have resupplied at sea, but tying up to a sub tender and its umbilicals in the midst of a busy sea-lane for as much as a day or two at a time made a U-boat dreadfully vulnerable.)

The Germans found an acceptable corollary in the merchant raiders—converted cargo ships studded with hidden guns and torpedo tubes, equipped with spotter airplanes and disguised as neutral-nation freighters immune from British attack. Merchant raiders could carry enough fuel to cruise for months at a time and could easily resupply from remote supply ships and at no-name atolls and lagoons a million miles from nowhere. They could patrol the distant South Atlantic, the Indian Ocean, the seas around Australia and New Zealand, the trackless Pacific—waters where U-boats rarely ventured. At one point, in fact, the disguised German merchant raider Michel, running roughshod through the Pacific in 1943, was the sole German warship on the high seas anywhere in the world.

During World War II, Germany launched just nine merchant raiders—all of them ex-freighters quickly converted to duty as moderately armed warships in disguise. These were by no means simple tramps with a couple of deck guns under tarps. They were maritime shapeshifters, with alterable smokestacks, telescoping masts, phony panels that could present a high forepeak one day and a fantail deckhouse the next. Each contained hidden compartments and movable bulkheads for the secreting of everything from prisoners to the raider’s airplanes. More than once, British boarding parties came and went without ever realizing they’d been aboard a German warship.

One raider, Orion, carried a second smokestack that could be erected to mimic the silhouette of a small passenger ship. A seaman was assigned to sit inside the dummy stack stoking a stove with trash and oil-soaked rags to make smoke. It was considered good duty, since the sailor was himself allowed to smoke—normally forbidden on watch.

Only savvy cargo skippers would sense anything was awry when a raider approached on a seemingly innocent converging course. Through binoculars they’d see typically casual Norwegian— or Dutch, Japanese, Greek or Portuguese— merchant mariners lolling about on deck in turtlenecks and dungarees, maybe a mate’s “wife” wheeling a baby carriage, an officer wearing a civvy derby, a white-aproned cook chucking slops over the lee rail. As the ships closed, the raider’s hidden fire controllers would measure the range while gunners charged their weapons inside phony deckhouses and water tanks or behind carefully counterweighted steel hull panels that could clang open in seconds. And, of course, the German naval ensign would quickly replace whatever flag the raider had been flying.

Interestingly, the use of phony ensigns, bogus steamship company logos and duplicitous national flags is legal in all conventions, treaties, laws, protocols and agreements governing the conduct of naval warfare. “Sailing under false colors” is a legitimate ruse de guerre, as long as the decoy flag is struck and other bogus national markings obscured by tarpaulins before the raider fires. Of course, some captains ignored this technicality and shot first. But the only World War II raider captain to be convicted of a war crime, Helmuth von Ruckteschell, was sentenced to seven years for abandoning castaways in lifeboats. (“It’s only 800 miles to the Canary Islands,” he reportedly told protesting officers and crew.)

Sailing under false colors was—and presumably still is— considered no more reprehensible than were ambushes, dummy airplanes erected on airfields, frontline soldiers without unit identifiers on their uniforms, bogus radio transmissions, planted false intelligence, use of an enemy’s stolen passwords or any other widely accepted ruses of war. It’s impossible to say who first disguised warships. It probably deserves the characterization “oldest trick in the book” and may have been around as long as there have been boats and wars. Certainly pirates both fictive and real used the dodge as early as the 16th century.

The infamous Confederate commerce raiders of the Civil War, which mutilated the Union’s maritime trade, did not sail under false colors, nor did the multi-turret German warships purpose-built to interdict shipping during both world wars. During World War I, however, the British developed Q-ships, heavily armed and thoroughly disguised merchantmen whose targets were not commerce but the nascent threat of U-boats. Torpedoes were expensive, so German sub skippers preferred to surface and use a deck gun to sink a harmless cargo carrier. If a British Q-ship could lure a U-boat to the surface, it would then hoist the Royal Navy ensign, reveal its ordnance and exchange fire. (It rarely worked. Britain’s 200- some Q-ships sank just 14 subs and lost almost twice as many of their own number.)

Unlike Ruckteschell, most raider captains were conscientious about rescuing their unfortunate victims. German crews largely comprised former merchant seamen and officers, who often felt a kinship with their opponents. Consequently, one of the raiders’ major challenges was the housing and feeding of shipwrecked seamen. Officers of the World War II raider Thor, which counted four British captains among its wards, supplied them with a bottle of good Scotch whisky once a week. Still, when lifeboats arrived alongside, raider officers were often compelled to direct seamen back to their vessel (assuming it wasn’t in flames or already sunk) to pack their duffels for a long cruise; castaways arriving with only the clothes on their backs were too big a drain on a raider’s stores.

The World War II raider Pinguin once rounded up more than 400 quasi-prisoners before it was able to transfer them to yet another seized ship—a Norwegian tanker then rerouted from the Indian Ocean to Occupied France. (During the voyage, a German boarding party of just 20 well-armed mariners watched over the prisoners, who now numbered 524, including the tanker crew.)

The best known of all German merchant raiders was SMS Seeadler (“sea eagle”), a full-rigged, three-masted sailing ship that during World War I masqueraded as a Norwegian windjammer, complete with a Norse-speaking German crew commanded by the legendary Count Felix von Luckner. Seeadler was one of the last sailing ships ever used for warfare—a deliberate choice. With no need for coal, this raider was restricted only by its need to occasionally provision and find fresh water.

Though von Luckner couldn’t have imagined it, World War II raiders carried Arado or Heinkel seaplanes, often two of them, hidden in holds that had been converted into hangar space. As a sophisticated launch catapult would too drastically alter a raider’s silhouette, the Germans instead used cargo booms to swing floatplanes out of the holds and plop them onto the ocean alongside the ship, where they did their often-ineffectual best to make open-sea takeoffs and landings—a challenge difficult enough for a stout PBY Catalina to handle, much less a flimsy Luftwaffe biplane.

When the floatplanes were usable, their function was twofold: to seek out likely targets and to cut the victim’s communications when they did find a ship. A good raider’s modus operandi was to attack fast and flee even faster. Letting a target get off a QQQ distress message that included its coordinates meant that somewhere a corvette or cruiser would be making steam and soon leaving a boiling wake en route to the scene of the crime. So the floatplanes, often painted with phony British Fleet Air Arm roundels, would circle their prey and suddenly swoop down, trailing a grapnel that stripped away the radio shack’s antenna before anyone aboard could react. (How is it legal for an airplane to continue to fly false colors as it attacks? Hard to say, unless ripping out an enemy ship’s antenna is not considered an offensive act.) Any distress messages that did get through probably aided the raiders’ cause, by throwing a fox into the henhouse and prompting the Royal Navy to overreact. Still, no raider captain wanted to be the hen.

Were Germany’s raiders successful? Yes, to the extent that they kept Royal Navy warships busy in the Pacific, the Indian Ocean, the Tasman Sea and other remote areas, dashing back and forth, burning fuel, to search for will-’o-the-wisp German attackers. But not so much when one considers the nature of the 886,000 tons of shipping and cargo they sank or captured: South American fruit, live New Zealand sheep (which raiders’ crews ate), jute, lumber, whale oil, corn, coal bound for noncombatant Argentina, and other miscellany. Rare was a raider’s target an ordnance-filled freighter or a tanker loaded with avgas. In fact, the great naval strategist A.T. Mahan derided commerce raiding as something of a distraction. First sink the enemy’s warships and eliminate its fighting power, he advocated, rather than wasting time on freighters filled with jute or dried fruit.

Regardless, by 1943 Germany had neither the time nor the materiel to launch any more trick ships that would likely never make it out of the Baltic anyway. Allied armies were no longer dependant on coasters trudging around New Zealand or banana boats hopscotching across the South Atlantic. Vast North Atlantic convoys carried the troops and supplies, and raiders were only useful against unarmed solo targets.

The raiders sailed for fewer than three years, sinking, capturing and mining an average of 16 ships each. Seven of the nine were themselves sunk (Stier, famously, by the Liberty ship Stephen Hopkins’ 4-inch fantail gun, in one of the most surprising mismatches of the war). The era of the raiders officially came to an end on Oct. 17, 1943, when the U.S. submarine Tarpon sent the raider Michel to the bottom of the Pacific. This happened not long after Michel had apparently blundered into the midst of a huge U.S. task force, fortunately on a dark night that allowed the little ship to discreetly fall back and away from its sudden companions. The war was changing faster than the raiders ever could.


For further reading, Stephan Wilkinson recommends: Hitler’s Secret Pirate Fleet, by James P. Duffy; Beware Raiders, by Bernard Edwards; and Phantom Raider, by Ulrich Mohr and A.V. Sellwood.

Originally published in the October 2008 issue of Military History. To subscribe, click here