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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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 Niš (1739) 1737 on the Russian side, but was forced to make peace with Ottomans at the separate Treaty of Belgrade, surrendering Northern Serbia, Northern Bosnia and Oltenia, and allowing the Ottomans to resist the Russian push toward Constantinople. In return, the Sultan acknowledged the Habsburg Emperor as the official protector of all Ottoman Christian subjects ("see Ottoman millet"), a position also claimed by Russia. The Austrian peace treaty compelled Russia to accept peace at Niš, ending the war with a partial Russian victory. Treaty of Niš (1739) The Treaty of Niš was a peace treaty signed on 3 October 1739 in