Kaiser Wilhelm II, a 19,361 gross ton passenger steamer built at Stettin, Germany, was completed in the spring of 1903. Designed for high speed trans-Atlantic service, she won the Blue Ribband for the fastest crossing in 1906. In the years before the outbreak of World War I, she made regular trips between Germany and New York, carrying passengers both prestigeous (in first class) and profitable (in the much more austere steerage). Kaiser Wilhelm II was west-bound when the great conflict began on 3 August 1914 and, after evading patrolling British cruisers, arrived at New York three days later.

For more than two and a half years, as armies exhausted themselves in the European trenches, Kaiser Wilhelm II remained inactive. She was seized by the United States Government when it declared war on Germany on 6 April 1917, and work soon began to repair her machinery, sabotaged earlier by a German caretaker crew, and otherwise prepare the ship for use as a transport. While this work progressed, she was employed as a barracks ship at the New York Navy Yard.

The U.S. Navy placed the ship in commission as USS Kaiser Wilhelm II (ID # 3004) in late August 1917. Her name was changed to Agamemnon at the beginning of September and active war work commenced at the end of October, when she left for her first troopship voyage to France. While at sea on 9 November 1917, she was damaged in a collision with another big ex-German transport, USS Von Steuben, but delivered her vital passengers to the war zone a few days later. Following return to the United Stated in December and subsequent repair work, Agamemnon again steamed to France in mid-January 1918 and thereafter regularly crossed the Atlantic as part of the massive effort to establish a major American military presence on the Western Front. The routine was occasionally punctuated by encounters with real or suspected enemy submarines and, during the autumn of 1918, with outbreaks of influenza on board.

In mid-December 1918, just over a month after the Armistice ended the fighting, Agamemnon began to bring Americans home from France. She made nine voyages between then and August 1919, carrying nearly 42,000 service personnel, some four thousand more than she had transported overseas during wartime. USS Agamemnon was decommissioned in late August and turned over to the War Department for further use as a U.S. Army Transport. Laid up after the middle 1920s, she was renamed Monticello in 1927 but had no further active service. Too elderly for use in the Second World War, the ship was sold for scrapping in 1940.