PORT CHARLOTTE, Fla. — A week after Eric W. Hall disappeared into the woods of Southwest Florida, his mother stood in a parking lot overlooking the Gulf of Mexico. She had asked for volunteers. Would they come?

Becky Hall’s son had experienced a flashback, fleeing a relative’s home after sensing that Iraqi insurgents had surrounded him. He was 24, a former Marine corporal from Indiana who had been medically discharged after a bomb ripped through his leg. Here, among the retirees and strip malls, he was a stranger.

And yet his absence spurred a community to action. More than 50 people stepped forward that first day in February. Others came later, young and old, contributing four-wheelers, pickup trucks, boats, horses, search-and-rescue dogs, and even a small plane.