The wreckage lay hidden, only a few miles offshore but 200 feet down, for more than 70 years.

The USS Eagle PE-56 sank on April 23, 1945, off the coast of Cape Elizabeth. Of the 62 crew members on board, 49 died. The 13 survivors were rescued from the water by a Navy destroyer that was in the area.

The Navy initially blamed the incident on a boiler explosion but determined in 2001 that it had been sunk by a German submarine. Still, the ship’s carcass remained elusive until last year, when a diver confirmed its location.

That stunning discovery will be featured in a three-part documentary series that airs beginning Sept. 22. “The Hunt for Eagle 56,” will premiere on the Smithsonian Channel and will highlight the efforts of a New England dive team to find the long-lost warship.

The Smithsonian Channel released a 2-minute trailer for the series on Tuesday that includes footage of the dive team, interspersed with interviews. The series also will feature never-before-seen accounts from survivors and relatives of Eagle 56 crew members.

The Eagle was a patrol boat but was equipped with weaponry to battle enemy submarines. On the day it sank, it was towing a practice target for bombers from the nearby Brunswick Naval Air Station. The wreck is one of as many as 1,000 shipwrecks off the coast of Maine that span centuries.

“The Hunt for Eagle 56,” was produced by South Portland-based Lone Wolf Media and its president Kirk Wolfinger, a veteran documentarian.