1972 in the Vietnam War the number of air raids against North Vietnam during all of 1971. Prime Minister Lon Nol declared President of Cambodia. Unlike the former Cambodian leader, Norodom Sihanouk, Lon Nol was a U.S. ally. The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam. The Khmer Rouge bombarded with artillery Phnom Penh, the capital city of Cambodia, killing more than 100 civilians. This was the heaviest attack on Phnom Penh since the Cambodian Civil War began in 1970. The United States boycotted peace negotiations in Paris with the North Vietnamese, citing
Treaty of Melno Treaty of Melno The Treaty of Melno (; ) or Treaty of Lake Melno () was a peace treaty ending the Gollub War. It was signed on 27 September 1422, between the Teutonic Knights and an alliance of the Kingdom of Poland and the Grand Duchy of Lithuania at Lake Melno (German: "Melnosee", "Meldensee"; Polish: "Jezioro Mełno"), east of Graudenz (Grudziądz). The treaty resolved territorial disputes between the Knights and Lithuania regarding Samogitia, which had dragged on since 1382, and determined the Prussian–Lithuanian border, which afterwards remained unchanged for about 500 years. A portion of the original border partially survives