Hell Below - The Wolfpack (2016, WW2 Historical Documentary)

The Rudeltaktik aka. wolfpack tactic was made famous by Admiral Karl Dönitz, 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 Dönitz'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.

Narrated by Mark Oliver

Hell Below is an event-based series charting the stealth game of sub sea warfare, tracking the dramatic narrative from contact to attack of the greatest submarine patrols of World War II. From the rise of the Wolfpack to the drive for victory in the Pacific, we profile the strategic masterminds and the rapid evolution of technology and tactics, as the threat of undersea warfare brings every sailor's worst nightmare to life. Expert analysis and stock footage are woven with narrative driven re-enactments filmed on authentic Second World War era submarines to place the characters at the heart of the action.

For more info:
https://en.wikipedia.org/wiki/Otto_Kretschmer