World War 1
Worldwar1.com: Trenches on the Web: Armory: U Boats: Assassins of the Seas
This site contains pictures, charts and general information on Germany's use of submarine warfare. It focuses on the second phase of submarine usage, i.e., to disrupt trade lines and enforce embargos.
The History Cat
The History Cat: America Enters the Ring
Describes the events leading up to America's entry into World War I and the changes that took place in America soon after. These included legislation such as the Selective Service Act and the Espionage and Sedition Acts, protests by...
Other
Destroyer History Foundation: Uss Greer (Dd 145)
Read about the first American shots of World War II fired by the USS Greer at a German U-boat in the North Atlantic before the U.S. entered the war.