Pentland Firth off the coast of Scotland by ramming her, the only time this tactic is known to have been successfully used by a battleship. March 19 – Pluto is photographed for the first time, but is not classified as a planet. March 26 – The Vancouver Millionaires win the Stanley Cup in ice hockey over the Ottawa Senators, 3 games to 0. March 28 – The first Roman Catholic liturgy at the newly consecrated Cathedral of Saint Paul, Minnesota, is celebrated by Archbishop John Ireland. April April 5 – Boxer Jess Willard, the latest "Great White Hope", defeats Jack Johnson with a 26th-round knockout in sweltering heat, at Havana, Cuba. Willard becomes very popular among white Americans, for "bringing back the championship to the white race". April 11 – Charlie Chaplin's film The Tramp is released in the United States. April 22 – WWI: Start of Second Battle of Ypres – Germany makes its first large scale use of poison gas on the Western Front. April 24 – Armenian genocide: deportation of Armenian notables from Istanbul begins. April 25 – WWI: Start of the Gallipoli Campaign by land forces (lasting until January 1916) – A landing at Anzac Cove is conducted by Australian and New Zealand Army Corps, and a landing at Cape Helles by British and French troops, to begin the Allied invasion of the Gallipoli peninsula in the Ottoman Empire. April 26 – Treaty of London: Italy secretly agrees to leave the Triple Alliance with Germany and Austria-Hungary, and join with the Entente Powers, in exchange for certain territories of Austria-Hungary on its borders. May May 1 – WWI: General Louis Botha, Prime Minister of South Africa, leads the army in the occupation of German South West Africa. The Battle of Gorlice begins. It is one of the bloodiest battles of World War I. May 3 – Canadian soldier John McCrae writes the poem "In Flanders Fields". May 5 – WWI: Forces of the Ottoman Empire begin shelling ANZAC Cove from a new position behind their lines. May 6 – Imperial Trans-Antarctic Expedition: The SY Aurora broke loose from its anchorage during a gale, beginning a 312-day ordeal. May 7 – WWI: Sinking of the RMS Lusitania: 's main rival, the British ocean liner , is sunk by Imperial German Navy U-boat U-20 off the south-west coast of Ireland, killing 1,198 civilians en route from New York