sep 3, 1939 - Battle of the Atlantic
Battle of the Atlantic, a contest between the Western Allies and the Axis powers for the control of the Atlantic sea routes. For the allied powers, the battle had three objectives: blockade the Axis powers in Europe, secure the allied sea movements, and free the military power project across the seas. This was a major turning point, due to the fact that it showed how powerful the allies were against the U-boats.
Added to timeline:
Key points for America during WWII