RMS Olympic was a British ocean liner and the lead ship of the White Star Line's trio of Olympic-class liners. Olympic had a career spanning 24 years from 1911 to 1935, in contrast to her short-lived sister ships, Titanic and Britannic. This included service as a troopship during the First World War, which gained her the nickname, Old Reliable. She returned to civilian service after the war, and served successfully as an ocean liner throughout the 1920s and into the first half of the 1930s, although increased competition, and the slump in trade during the Great Depression after 1930, made her operation increasingly unprofitable. Olympic was the largest ocean liner in the world for two periods during 1910–13, interrupted only by the brief tenure of the slightly larger Titanic (which had the same dimensions but higher gross register tonnage) before the German SS Imperator went into service in June 1913. Olympic also held the title of the largest British-built liner until RMS Queen Mary was launched in 1934, interrupted only by the short careers of Titanic and Britannic.[4][5] Olympic was withdrawn from service and sold for scrap in 1935; demolition was completed in 1937. The other two ships in the class had short service lives: in 1912, Titanic collided with an iceberg on her maiden voyage and sank in the North Atlantic; Britannic never operated in her intended role as a passenger ship, instead serving as a hospital ship during the First World War until she hit a mine and sank in the Aegean Sea in 1916.