WASHINGTON, Feb. 11 — Samuel W. Koster, who was an Army major general in 1968 and became the highest military officer to be charged in the massacre of South Vietnamese civilians at the village of My Lai, died on Jan. 23 at his home in Annapolis, Md. He was 86.
The cause of death was renal cancer, said his daughter Nancy Sroka of Crofton, Md.
General Koster was a major general in command of the Americal Division when some of the unit's soldiers killed hundreds of defenseless men, women and children on March 16, 1968. The Americans had not come under fire, nor were any Viet Cong found in My Lai.
The massacre, disclosed in late 1969 by the journalist Seymour M. Hersh, was for critics of the Vietnam War a symbol of the United States military's moral bankruptcy. Those who believed in the United States' cause were also horrified and baffled at the soldiers' conduct.
Early in 1970, General Koster and 13 other officers were charged with trying to cover up the massacre. General Koster had been in a helicopter over the My Lai area on March 16, 1968, and insisted that his subordinates never told him a mass killing had occurred.
"I accepted those reports," General Koster testified in 1971 at the court-martial of another defendant. The general said he had been under the impression that only about 20 civilians had been "inadvertently killed" by artillery, helicopter guns and "some small-arms fire."
The Army concluded that General Koster "did not show any intentional abrogation of responsibilities," and the criminal charges against him were eventually dismissed. Nevertheless, the Army found, he had failed to investigate reports of the mass killings adequately. He was censured, stripped of a Distinguished Service Medal and demoted one rank, to brigadier general.
In dismissing the criminal charges, Lt. Gen. Jonathan O. Seaman, commanding general of the First Army, said he had considered "the long and honorable career" of General Koster.
General Koster had left Vietnam to become superintendent of the United States Military Academy in June 1968. When he announced his resignation in 1970 as the cover-up investigation was swirling around him, he was given a 90-second ovation by the 3,700 West Point cadets, who were grateful to him for having broadened the academy's curriculum and for doing away with much of the hazing that had made life miserable for plebes.
Instead of retiring after his demotion, General Koster became deputy commander of the Army's Test and Evaluation Command at the Aberdeen Proving Grounds in Maryland. He left the Army in 1973.
Born in West Liberty, Iowa, on Dec. 29, 1919, Samuel Koster graduated from West Point in 1942. He was a regimental executive officer in Europe in World War II and directed the Eighth Army's guerrilla warfare operations in the Korean War. He assumed command of the Americal Division in 1967. His decorations included the Silver Star, Legion of Merit and Bronze Star.
General Koster is survived by his wife of 63 years, Cherie; three sons — all Army colonels — Samuel Jr., of Burke, Va.; Robert, of Vienna, Va.; and Jack, of Picatinny Arsenal, N.J.; two daughters, Susanne Henley-Ross of Annapolis and Mrs. Sroka; 15 grandchildren; and six great-grandchildren.
Lt. William L. Calley Jr., a platoon leader at My Lai who was court-martialed and found guilty of murder, was the only officer convicted of criminal charges in connection with the massacre. Another officer, Col. Oran K. Henderson, a brigade commander at My Lai, stood trial and was acquitted of cover-up charges. Other officers were punished administratively.
General Koster, who had called the Army's censure of him "unfair and unjust" and based on "faulty conclusions," spent more then a decade trying to clear his name. He lost an appeal to the Army Board for Correction of Military Records. Then, in 1982, the United States Court of Claims refused to lift the sanctions that had been lodged against him.
That year, General Koster reflected on the war in an interview with The Washington Post. "Getting into Vietnam in the first place was where we made a mistake," he said. "Before you fight on the continent of Asia, you ought to have an overwhelming reason to be there, and I don't think we had one."