In Mr. Beyer’s documentary, Mr. Seltzer recalled his first reaction when he was told that the purpose of preparations for the 23rd was to fire the enemy at him and his comrades.
“We came to the conclusion,” he said, “that it was a suicide suit.”
Mr Beyer said three members of the phantom army were killed and around 30 injured. He suggested two reasons for the relatively low number of casualties: the unit projected great force through its disappointments, possibly pushing back the enemy; and the soldiers were not always at the front, which minimized their vulnerability.
After the war, Mr. Beyer returned to architecture. Over the years he has designed the Utica Memorial Auditorium in Utica, NY (now the Adirondack Bank Center), which is renowned for its cable suspended roof system; the West Point and US Merchant Marine Academy buildings; and the East Coast Memorial in Battery Park, Lower Manhattan, which honors soldiers, sailors, marines, coast guards, merchant seamen and airmen who died in action in the Atlantic during World War II . He continued to work until January 2020.
Besides his son, Mr. Seltzer is survived by two grandchildren and three great grandchildren. His wife, Molly (Gold) Seltzer, died in 1994.
One night in July 1944, soldiers of the 603rd were on a farm in Normandy, where they moved an anti-aircraft battery and replaced it with a rubber battery, as part of an operation to cover the movement of the second armored division with dummy tanks and guns to trick the Germans into believing that the division had not left.
The farmer, who was angry at the noise that had been made by the real guns, approached the soldiers and said, “Boom boom again?” Punching a gun, not knowing it was a fake.
“His hand bounced up and down and he said ‘Boom boom ha ha’,” Mr. Seltzer told Mr. Beyer in the interview filmed for the documentary but not used. “It became a synonym in the 603rd.”