One of the strangest naval battles of the First World War took place in September 1914, when a British “armed merchant cruiser” engaged a German “auxiliary cruiser” that was disguised as … itself.
The decades from the 1890s to the 1910s were the golden age of the Atlantic ocean liners. British and German passenger liners plied the seas carrying rich tourists and poor immigrants between Europe and the United States. Many of these ships were subsidized and partially paid for by the British or German governments, under the agreement that in time of war they would be taken over by the military and used as hospital ships, troop carriers, or convoy escorts. And so when the First World War broke out in August 1914, civilian passenger ships from most European countries found themselves in port being hastily refitted for military service.
One of these was the RMS Carmania. Built in 1905 by the British Cunard line, Carmania was an experiment: she was one of the first large passenger liners to use the newly-developed steam turbine engines. Her sister ship RMS Caronia used the older steam reciprocating engines so the two could be directly compared and assessed. (As a result of this test, Cunard decided to equip its two planned larger luxury liners, the Lusitania and Mauritania, with steam turbines.) And as part of the arrangement with the Royal Navy, both the Carmania and Caronia were constructed with fittings that allowed them to be quickly armed with naval deck guns in the event of war.
In Germany, the Hamburg-South America Line introduced a new liner in April 1914, named the SMS Cap Trafalgar. Intended for passenger service between Germany and Brazil, she was not as big as the northern Atlantic liners, but still displaced 16,000 tons. And like her British counterparts, the Trafalgar was designed to be readily converted to military service with the German Kriegsmarine in the event of war.
That war came suddenly in August 1914.
The Trafalgar was in Buenos Aires when the Great War broke out, and promptly sailed into the neutral port of Montevideo where she was met by the German gunboat Eber, whose crew hastily fitted a number of 4.1-inch naval guns and 1-pounder quick-firing “pom-pom” guns onto Trafalgar’s decks to allow her to attack British merchant vessels. Further, to disguise her and allow her to closely approach her intended targets, it was decided to alter the Trafalgar to make her look like a British vessel. So, one of the Trafalgar’s funnel stacks was removed and her paintjob was altered to make her look like the British Cunard liner Carmania. (It just so happened that the Germans had a newspaper advertisement with a photo of the British ship.)
The real RMS Carmania, meanwhile, had also been requisitioned by the Royal Navy and was in port in Liverpool having her own 4.7-inch guns fitted. The process took only two weeks, and by the end of August the now-armed Carmania was in Bermuda, where she was assigned to protect British shipping in the Caribbean.
The also-now-armed German ship Trafalgar had been sent to a small German base on the island of Trindade, off the coast of Brazil, where she was assigned the task of hunting down and attacking British merchant ships. The British promptly ordered the Carmania to find her and destroy her. And so when the Carmania arrived at the tiny island on September 14, her crew got the surprise of their life: there, in the harbor in front of them, was the German liner SMS Cap Trafalgar, disguised as the RMS Carmania and fully armed.
The Trafalgar tried to run away, but the Carmania, with her better turbine engines, caught up. The battle that followed was akin to two medieval knights fighting with peashooters: although neither ship had any armor to speak of, their naval guns were intended for use against small cargo ships, not large ocean liners. As they blasted away at each other, both ships tried to get closer for greater effect. Hundreds of shells were fired by both sides: the British had the advantage of larger projectiles, but the Germans could fire their guns much more rapidly.
After about two hours, the Carmania had been hit by at least 70 German shells and her bridge was set afire. The Trafalgar, which had taken numerous hits along her waterline, was listing heavily. Finally the Trafalgar rolled onto her side, floated there for several minutes, then slipped beneath the sea. She had never struck her flag in surrender. It took hours for the Carmania’s crew, their ship barely afloat, to get her fires under control.
Just then, another ship appeared in the distance. Both the Trafalgar and the Carmania had desperately sent radio messages to nearby friendly ships pleading for help, and now it was the German armed auxiliary Kronprinz Wilhelm (another converted passenger liner) which arrived first. The Carmania, badly crippled, was a sitting duck. But amazingly the German ship turned and sailed away: her captain feared that there were British warships in the area. And he was correct: later that day the British Navy cruiser HMS Cornwall arrived at the scene, picked up 270 survivors from the Trafalgar, and then escorted the Carmania into the nearest port for repairs.
In the exchange of gunfire, nine crew members of the Carmania had been killed, while the Trafalgar lost around 50, including her captain.