Maine: When Portland was on the front

For much of American history, Maine's largest city was of prime strategic importance. Its capacious harbor -- easily capable of sheltering an entire navy -- has been the closest major U.S. port to Europe since the Revolution, and military planners defended it as such.

The result: Casco Bay is littered with military fortifications, from the remnants of Revolutionary earthworks to the listening posts and anti-aircraft emplacements rushed into being in the run-up to World War II, when planners feared a German invasion. I probe their story in the current issue of Down East, now available online.