“I’ve had many nightmares over the years,” Gen. Al Ungerleider once said, “about what happened at Nordhausen.”

He was 23, he recalled, an Army lieutenant and a Jew. He had been “battle-tested” at Normandy in June 1944, he said, riding the second wave of the assault on Omaha Beach and then pounding his way through France, Belgium and Germany.

But Nordhausen, in central Germany, was different from those other experiences, said Gen. Ungerleider, who died of pneumonia in Washington on Feb. 13. He was 89.

He approached Nordhausen on April 17, 1945, a date, he said, that was “burned into my soul.” His orders were to take and hold part of an industrial complex there.

His detachment had to fight its way through the gates and the barbed wire, dodging machine-gun fire from enemy soldiers hiding in towers near the entrance.

After his men took out the enemy, the camp inmates began to appear. They were so emaciated that only a few could stand upright. Some fell over, he recalled. Still others were lying in bed, covered in lice and sores.

Lt. Ungerleider sent his men to check the grounds for remaining Nazi soldiers. He said they captured 44 SS troopers, all of whom surrendered.

“Billy Millhander, one of my soldiers, and I entered a large building at the center of the camp and discovered 10 huge ovens — crematoriums — but I didn’t know that at the time,” he told the authors of the 2005 book “War Stories III: The Heroes Who Defeated Hitler.”

“The ovens were cold, and the doors were closed,” he said. “I looked at Millhander and said, Billy — have your M1 rifle ready. I’m going to open each door of these things and see if anyone’s hiding inside.”

The first four contained ashes. But when the lieutenant opened the fifth, Millhander immediately fired several rounds, killing an armed German guard.

“He just toppled forward, dead,” Gen. Ungerleider said, “and Billy got a nice Lugar pistol out of the deal.”

They returned to the main yard, and Lt. Ungerleider spoke a mixture of Yiddish, English and German to the camp inmates. He asked how many were still alive. The reply came: maybe 250 out of thousands.

He asked what they were making at the plant. Someone said V-2 rockets, missiles that were launched against England.

“And that’s when the enormity of the evil that the Germans were doing to these people hit me,” he said in “War Stories III.” “And this was a slave labor camp, not a death camp. They were making a product for the war effort. The first thought that came into my mind is how the Germans could take [thousands of people] and put them to work. How could they not feed them, take care of their medical needs, not clothe them?”

He led the survivors in the mourner’s kaddish, the Jewish prayer for the dead.

Alvin David Ungerleider was born July 30, 1921, in West New York, N.J. He was 8 when his father, an insurance salesman, died. The family resettled in Carbondale, Pa., where his mother took in boarders for income.

After high school, in 1942, he joined the Army. As a young officer, he had 50 men under his command when he participated in the Normandy invasion. Shrapnel from mortar fire wounded him in the right thigh and left forearm.

In addition to two awards of the Purple Heart, he received two Bronze Star Medals for valor. His other decorations, for later service in Vietnam, included three awards of the Legion of Merit.

During his military career, he received a bachelor’s degree in public administration from George Washington University, and he attained the rank of brigadier general. His final active-duty assignment was commanding the Aberdeen Proving Ground in Maryland. He settled with his family in the Washington area after his retirement from the Army in 1978 and was a Burke resident.

Survivors include his wife of 63 years, Ruth Golden Ungerleider of Burke; three children, Neil Ungerleider of Boxford, Mass., Ilene Ungerleider of Somerville, Mass., and Dan Ungerleider of Burke; a sister; and six grandchildren.

During his Army career, Gen. Ungerleider maintained ties to his Jewish roots. When there were no synagogues or religious schools for his children, he improvised. During Passover in Paraguay in the late 1950s, he had a Jewish welfare agency send supplies.

In the late 1970s and early 1980s, he was the executive director at two synagogues, Olam Tikvah in Fairfax County and what is now Beth El Hebrew Congregation in Alexandria. He volunteered as a docent at the U.S. Holocaust Memorial Museum.

In 2004, after visiting the National World War II Memorial in Washington, he reflected on his own wartime experience and his hope for future generations of soldiers.

“What we did is almost mind-boggling,” he told the publication Washington Jewish Week. “On the other hand, we were young and pressed forward regardless — and if they had to do what we had to do, I’m sure they would bring up the necessary courage.”