A deep water dive team search the seabed off the coast of Northern Ireland for the forgotten shipwrecks of World War II's Battle of the Atlantic. Jules Hudson helps identify the wrecks, and reveals how the city was critical to Allied victory.

Maritime historian and underwater explorer Ian Lawler leads a team of deep water divers to the seabed off Northern Ireland. He and the team are searching for the forgotten shipwrecks of the war's longest, most epic naval campaign.

Presenter Jules Hudson joins Ian and two naval experts as they attempt to piece together the stories of the wrecks from the dive team's underwater footage. What they discover reveals the unique role played by the city of Derry-Londonderry in fighting the battle. And while the divers continue their mission at sea, Jules hunts on land for the final clues to the forgotten story of the battle.

In this episode, Jules explores how an airbase in Derry provided the vital air cover the Allies needed to win the Battle of the Atlantic. And at sea, the divers uncover the German U-boat wrecks that reveal how the battle finally swung in the Allies favour. They also find the remains of submarines sunk as part of the German surrender in Derry, and dive to the wreck of Hitler's deadliest U-boat. Show less