World War One began in 1914, and it involved the largest navies in the world. The British, German and French navies had lots of dreadnoughts at their disposal, but needed extra ships for transporting troops and commerce raiding.
As such, those navies added ocean liners to their fleets provided by some of the foremost shipping companies such as White Star Line, Cunard and Norddeutscher Lloyd.
After Britain declared war with the German Empire, the Admiralty requisitioned a number of famous ocean liners in 1914. Among them was the Mauretania, the Blue Riband holder, which was subsequently refitted and shipped more than 10,000 troops to Greece in 1915. Like other liners converted to troop transport ships, the Admiralty painted the Mauretania’s hull with dazzlepaint to camouflage it from German U-boats that were expanding their operations.
No German U-boat ever intercepted the Mauretania, but Cunard’s Lusitania was not so fortunate. That was one of the few ocean liners which continued transatlantic crossings in 1915. In 1915, the German embassy stated that any ship flying the British flag would become a potential target for their U-boats. Nevertheless, Lusitania still sailed with about 1,959 passengers aboard in May 1915.
A German U-boat intercepted the Lusitania off the Irish coast in May 1915. The U-boat fired a torpedo at the Lusitania that left a huge hole at the ship’s side. The impact of the torpedo ensured the ocean liner sank within 30 minutes. There was not nearly enough time to effectively evacuate the ship, and about 1,195 passengers were lost at sea.
Even though there were Americans aboard the liner, the Lusitania’s sinking was not enough to end US neutrality in the war during 1915. However, the Germans pledged to scale down their U-boat operations thereafter. Only when the German navy resumed unrestricted submarine warfare in 1917 did the United States declare war with the Germany.
The Carmania was a Cunard liner that the Admiralty converted to an armed merchant cruiser. As an armed cruiser, the Carmania intercepted the German ship Cap Trafalgar off Trindade Island. The Cap Trafalgar was also an ocean liner converted to a cruiser, and there was relentless firing between the two ships for more than an hour. The battle ended with the Carmania sinking the former German ocean liner. With 304 holes in her hull and decks ablaze the Carmania quickly made her way to a nearby port for repairs.
The Admiralty also added White Star ocean liners to their fleets. The Olympic-class liners RMS Olympic and Britannic were the largest afloat, and were duly converted to troop and hospital ships. The Admiralty added a 12-pounder gun and a couple of 4.7 guns to the Olympic before it began transporting troops. Then it began transporting troops to Mudros in the Mediterranean, and later sailed as a hospital ship.
The RMS Olympic sailed into British waters in May 1918 transporting US troops, where it met up with four US cruisers that provided further escort. As the Olympic sailed into the Channel, a lookout aboard the ship spotted the German U-boat U-103 lying still at the surface. Gunners aboard the Olympic opened fire, but they were too close to sink the submarine with their guns. As such, the Olympic rammed and sank the U-boat. The impact twisted the Olympic’s stern, but the ship did not leak any water and reached port.
The Admiralty requisitioned the Britannic as a hospital ship in 1915. The ocean liner continued sailing into the Mediterranean in 1916 until November. On its final November trip the Britannic sailed into the Kea Channel where a German U-boat had laid mines. There an explosion shattered the ship at the starboard bow. As water flooded the Britannic, Captain Bartlett gave the orders to abandon ship. Distress calls were promptly picked up by a number of nearby destroyers and cruisers that rushed to the Britannic. Those ships rescued most aboard the Britannic, and White Star later received the German ship SS Bismarck (later retitled Majestic) as a replacement for their lost liner.
France II was one of the French ocean liners converted to a troop transport ship during the war. It was initially converted to an auxiliary cruiser, but as it had high fuel consumption was rebuilt as a troop ship. The ship transported troops to the Dardanelles in 1915. When the United States joined the war, France II transported troops from the USA to Europe in 1917 and 1918.
The German shipping company Norddeutscher Lloyd also had some great ocean liners in their fleet such as the Kaiser Wilhelm der Grosse and Kronprinz Wilhelm. Both of those ocean liners had set new Blue Riband records for transatlantic crossings. Their extravagant interior décors had also raised the bar for naval architecture.
After the outbreak of World War One, those German ocean liners went to war as merchant cruisers. The German navy adopted a war on commerce targeting merchant ship supplies. For that they deployed not only their U-boats, but surface raider ships such as the converted Wilhelm Der Grosse and Kronprinz Wilhelm.
The Kaiser Der Grosse sank three ships during 1914. Later in August 1914, the same month it sank the three ships, the Kaiser Der Grosse approached the west coast of Africa and stopped at Rio de Oro to refuel. As colliers refuelled the ship, the British cruiser HMS Highflyer approached the Kaiser Der Grosse. The German commerce raider quickly steamed out to engage the cruiser, but ran out of ammunition during the skirmish. To ensure the ship was not captured, Captain Reyman ordered his crew to scuttle the Der Grosse.