Capt. Shawn McMickle, the soldiers’ company commander, said that he’s responded to three Civil War-era explosives since he’s served with the Army in the Pacific Northwest.

Typically, construction crews and loggers find the war relics buried in the ground or in the brush. But they can — and do — turn up in more unusual places.

On Jan. 21, members of the Fort Belvoir, Virginia-based 55th EOD Company responded to a call from police and firefighters in Georgetown, Maryland. They’d found a Civil War cannonball in the chimney of an 1890s townhouse.