March 9 Under orders from President Richard Nixon, the Defense Department removes secrecy restrictions on U.S. military operations in Laos. Previously, all American casualties in Laos were included with losses in South Vietnam.
March 17 The Army files courts-martial charges against 14 officers for their involvement in the March 16, 1968, My Lai Massacre and/or the cover-up. Only one was convicted, 2nd Lt. William Calley, on March 31, 1971, although the 23rd Infantry Division (Americal) commander, Maj. Gen. Samuel Koster, was demoted to brigadier general and censured.
March 18 Gen. Lon Nol, Cambodia’s prime minister, deposes the kingdom’s ruler, Prince Norodom Sihanouk, in a coup. In 1972, he established the U.S.-backed Khmer Republic with himself as president.
March 23 For the first time, America’s most powerful conventional weapon, the 15,000-pound…