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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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 the Triple Alliance from the mouth of the Apa River with the Paraguay River up to its mouth in Bahia Negra. A treaty of Peace, Commerce and Navigation was signed on December 13, 1873, between Paraguay and Uruguay. As with the Brazilian treaty, Paraguay recognized the expenses, damages and detriments of Uruguayan campaign. Both governments also committed to return all prisoners of war and reopen commerce on the rivers. A Treaty of Peace with Argentina was signed on February 3, 1876, between Paraguay and Argentina. In it, Paraguay recognized all war expenses as well as the damages and detriments caused to Argentine public