He had pneumonia, said his son Dennis Jr.

Less than six months after graduating from the US Military Academy in 1944, General McAuliffe was serving with the 89th Infantry Division in Europe as a field artillery officer. In a brief account of his career written for his family, he said that he ‘‘walked across all of Germany’’ in the final months of World War II.

In April 1945, he was a young lieutenant in a unit that entered the Ohrdruf concentration camp, part of the larger German concentration camp of Buchenwald. Ohrdruf was the first Nazi concentration camp to fall into Allied hands, and, as he wrote, ‘‘I was among the first Americans to see it.’’

He recalled a scene that was beyond horrific. Among other things, he saw the corpses of three US airmen who had been shot in the head.

‘‘Inside the camp,’’ he wrote, ‘‘were thousands of bodies, of mostly Jewish men, stacked 3 to 12 feet high, unclothed, awaiting burning.’’

In archival films of the liberation, General McAuliffe can be seen ordering Nazi officials and townspeople to enter a death chamber and view victims of the Holocaust. When three top Army generals — Dwight D. Eisenhower, Omar N. Bradley, and George S. Patton — visited the camp, General McAuliffe was close enough to see the expressions on their faces.

‘‘General Patton became ill,’’ he wrote, ‘‘excused himself, and threw up.’’

Days later, Eisenhower described the scene in a letter to General George C. Marshall.

‘‘The visual evidence and the verbal testimony of starvation, cruelty, and bestiality were . . . overpowering,’’ he wrote. ‘‘I made the visit deliberately in order to be in a position to give first-hand evidence of these things if ever, in the future, there develops a tendency to charge these allegations merely to ‘propaganda.’ ’’

General McAuliffe participated in another grisly military operation later. As commander in chief of the Army’s Southern Command in Panama in 1978, he helped organize the recovery and transportation of bodies from Jonestown, the settlement in Guyana where about 900 followers of cult leader Jim Jones committed suicide.

After retiring from the Army as a three-star general in 1979, General McAuliffe was named by President Carter to be administrator of the Panama Canal Commission. He managed the difficult transition of the ­canal to Panamanian control, as mandated by a treaty.

During the 10 years he held the post, General McAuliffe tried to fend off interference from the Panamanian military and government, as well as ­demands from Congress. He supervised a workforce of 8,000 that included almost 2,000 Americans, many of whom felt isolated and scorned in an increasingly hostile place.

Less than two weeks before General McAuliffe retired in 1989, US forces invaded Panama in an attempt to force strongman Manuel Noriega from power. The 50-mile canal was temporarily closed to traffic for the first time since it opened in 1914.

In testimony before Congress in 1991, General McAuliffe said he had only 45 minutes’ warning before the invasion began.

‘‘Had it been hit by artillery or mortar fire, it might well have caused a lengthy shutdown of the canal,’’ he said. ‘‘Pure luck, and nothing else, prevented a potential disaster.’’

Dennis Philip McAuliffe, known casually as Phil, was born in New York City.

He graduated from the US Military Academy at West Point, N.Y., on June 6, 1944, D-day. He received a master’s degree in electrical engineering from the University of Pennsylvania in 1950.

From 1967 to 1969, he was executive officer to General Earle Wheeler, chairman of the Joint Chiefs of Staff. In Vietnam in 1969 and 1970, General McAuliffe was the senior adviser to Lieutenant General Do Cao Tri, once described by Time magazine as the ‘‘best fighting general’’ in the South Vietnamese Army. Tri was later killed in a crash of General McAuliffe’s old helicopter.