U-boat, German Submarine Warfare in WWI & WWII

German u boat attack hi-res stock photography and images - Alamy

Shipwreck of WWI German U-boat Discovered off Virginia in 400ft of

How German U-Boats Were Used in WWI—And Perfected in WWII

U boat in world war i hi-res stock photography and images - Alamy

Recovered WWI German U-Boat Revives 'Sea Monster' Tales

German U-boats from WWI and WWII seem to look the same and be used

World War I Monitor National Marine Sanctuary

H I Sutton - Covert Shores

Submarines in World War II (U.S. National Park Service)

The One Time a German U-Boat Wound Up in New York City's Central Park

Unrestricted Submarine Warfare and How It Caused Germany to Lose WWI