STONY BROOK, N.Y. — Every morning, Lieutenant Michael Settanni wakes up next to his bunkmate, Cpl. Ben Gebbia, in a modest room in a home shared with about 350 other military men.

“It’s better than a barracks,” joked Mr. Settanni, who is 101 and whose head still carries pieces of shrapnel from a shell that exploded behind him on Omaha Beach as he led a tank brigade into France to fight German soldiers on D-Day: June 6, 1944.

The wounds to Mr. Gebbia, who is 95 and who served as a medic, were not physical but they were just as scarring. After being dropped by ship onto Normandy Beach during the invasion, he tended to scores of wounded American soldiers as his regiment fought its way to Germany, where his part in the liberation of two concentration camps left him with horrific memories of emaciated prisoners.

These two Army veterans have a friend, two floors down, named Julian Oleaga, 89, who as a slightly built 19-year-old was dropped into chest-deep water while carrying equipment that felt heavier than his own weight. Private Oleaga waded through the surf to storm the beach with his regiment during the D-Day invasion.