The wolfpack tactic was made famous by Admiral Karl Donitz, Hitler's mastermind of submariners. His strategy: to send teams of U-boats to bear against the convoys of ships heading from Canada to Britain, cut maritime lifelines, and starve the enemy into defeat. Take a deep dive into the North Atlantic as we go above and below sea level to relive one of the first attacks of Donitz's lethal subs in 1940, headed by leader of the pack Commander Otto Kretschmer. Then follow Britain's war strategists as they race to combat this new deadly attack.

It's January 1943 in the Pacific and American submarine skipper Dudley Morton is just 10 days into his first patrol aboard USS Wahoo. His mission: to sink Japanese ships and disrupt supply lines. This aggressive strategy is a radically new tactic for the U.S. Navy, and Morton is just the man to carry it out. See these water wars up close and witness Morton take on entire Japanese convoys above and below the Pacific in this thrilling exploration.