When the U boats were unleashed on the world's shipping

How to end a filibuster: World War I and the origin of the cloture rule

Unrestricted U-boat Warfare National WWI Museum and Memorial

Building Modular Motherships: Denmark and Singapore Lead the Way

Canada pledges to work with U.S. over claims to Arctic sea floor

K-Ships vs. U-Boats National Air and Space Museum

Wreckage of cargo ship sunk by German U-boat in WWI found at bottom of Irish Sea - Mirror Online

MEDIA MONDAY: U-Boat sinks Schooner in the First World War (1917) - Hudson River Maritime Museum

During the Second Happy Time, the destroyer USS Roper struck a blow against marauding U-boats. - Warfare History Network

Mother Gives Birth During U-Boat Attack

Kaiten - Warfare History Network

German U-Boats on American Shores: Operation Pastorius & Beyond - Warfare History Network

20 Facts About the Battle of the Atlantic in World War Two

The WW1 Q-Ships Were Heavily-Armed Decoy Vessels, Designed To Lure Unsuspecting U-Boats Into A Trap

Reviews for The Caribbean War Front in World War II: The Untold Story of U- Boats, Spies, and Economic Warfare — Markus Wiener Publishers

Who sank the most U-boats in WW2? - Quora