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.

Just one month after the Japanese attack on Pearl Harbor, another enemy brought World War II to American shores, not through the air but beneath the sea. This is the story of Operation Drumbeat, German Admiral Karl Donitz's campaign to send U-boats to the doorstep of the U.S. and attack Allied merchant shipping from Newfoundland to North Carolina. Through archival war footage and military expert testimony, we reveal how the Nazis managed to hammer our coast again and again and why the U.S. Navy was unable to stop them.

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.

A Nazi U-boat heading back for repairs unintentionally cruises right into the middle of a large Allied convoy on March 16, 1943. It is a lucky accident that sets the stage for the largest convoy battle of World War II. Relive this momentous chapter in the war for the Atlantic, an intense game of chess pitting Admiral Karl Donitz's wolf pack against a battered British Navy. It's a three-day showdown with unparalleled violence and unexpected outcomes that will turn the tide of the war.

The USS Harder, led by Commander Sam Dealey, sank multiple Japanese destroyers, rescued Allied operatives from capture in Borneo, and outmatched many rival ships and aircraft to return home. And that was during just one patrol. Take a deep dive aboard this submarine as we relive this incredible war patrol in the spring of 1944, and witness the events that accelerated the campaign against the Japanese and earned Dealey the Medal of Honor.

Submarine commander Dick O'Kane participated in the most successful attacks on Japanese ships during World War II, until his luck, and the last torpedo he fired, took a dramatic turn. We track O'Kane's successful career, first as a protege aboard the legendary USS Wahoo, and then as Commander of the short-lived but lethal USS Tang. Through expert testimony, we relive O'Kane's seminal triumphs, and the tragic path of his last warhead.