PHILADELPHIA (AP) — The way Ernie Gross and Don Greenbaum laugh and tell jokes with the ease of old friends, it's easy to assume the dapper octogenarians have known each other forever.

In reality, they only met a few months ago. Their familiarity doesn't come from shared memories of a childhood playground or a high school dance but a far darker place: Both men were at the Dachau concentration camp on the day its 30,000 prisoners were liberated by American soldiers in 1945.

Greenbaum, 87, and Gross, 83, don't think they met that day in Dachau but nevertheless share a bond. They met after Gross, who lives in Philadelphia, saw a mention in a local newspaper last November about Greenbaum, a Philadelphia native now living in suburban Bala Cynwyd....