One of the greatest convoys of World War II occurred during May of 1940 and yet, hardly anything has been written about it. Shortly before the start of WWII, passenger ships were experiencing a resurgence of popularity after a decline in the 1910s-1920s. Cunard White Star in cooperation with the British government, had obtained two of the largest cruise ships afloat before the start of the war and had recently completed a third, RMS Mauritania. With the declaration of war with Germany, many of these ships were shuttled to New York to protect them from German submarines. In early 1940, RMS Mauritania lay idle in New York, docked alongside RMS Queen Elizabeth, RMS Queen Mary, and the French Line's SS Normandie, the only time all three of the world's largest ocean liners were ever berthed together. Then on 20th March, RMS Mauritania, RMS Queen Elizabeth and RMS Queen Mary slipped down the Hudson and away from New York. Their work for the war effort was about to begin. Sailing from New York via the Panama Canal, they arrived in Sydney to be converted for their new role. This conversion work was carried out in April where some armaments were attached and the ships painted over in battle grey. The names of the vessels were blackout but they could be recognised by their shape. They were painted battleship grey, even the numbers on the funnels were grey, but the numbers on the bow were in black. The ships had been stripped down with all the brass railings taken off so sunlight could not reflect. As remembered by one seaman, "We sailed into the Sydney harbour and passed the Queen Elizabeth loaded with Aussies; then pulled into the wharf opposite to where the Isle of France was tied up. There we loaded on more food supply plus twelve hundred Aussies and by joves they are great lads, and there was no leave for us there, so we were very disappointed as Sydney was a town where we wanted leave." In May, the ships left Sydney as part of one of the greatest convoys ever mustered for the transport of troops, Convoy US.10. With RMS Mauritania were RMS Queen Mary, RMS Queen Elizabeth, and RMS Aquitania bound for the River Clyde via South Africa. The Queen Mary embarked 6,000 Australian troops and the Queen Elizabeth another 5,600. Before departure they were joined by the Mauritania with 4,400 New Zealand troops and Aquitania with 2,000 troops. Other notable liners in this great convoy were RMS Empress of Britain, RMS Empress of Canada, RMS Empress of Asia, and SS Nieuw Amsterdam. The voyage was uneventful and the ships parted ways soon after, continuing their war effort as transport ships. Little to none has been written about this convoy. During the early stages of the war the RMS Mauritania transported Australian troops to Suez, India and Singapore but later she mainly served in the North Atlantic. Queen Elizabeth and Queen Mary were both used as troop transports during the war. Their high speeds allowed them to outrun hazards, principally German U-boats, usually allowing them to travel outside a convoy. All of the ships went on to more illustrious and historic events, but for a time in the spring of 1940, they were part of the greatest convoy of WWII.