The Sea Battles
Three theatres, five years, four million tons of shipping on the bottom.
3 September 1939 – 8 May 1945
The Battle of the Atlantic
The longest continuous campaign of the war: five years of U-boats against Allied convoys.
Royal Navy / IWM
Principal Events
- Sep 1939
SS Athenia sunk by U-30
The first British ship sunk — torpedoed on the day war was declared.
- Oct 1939
HMS Royal Oak
U-47 penetrates Scapa Flow. 835 dead.
- Jun 1940
First "Happy Time"
Fall of France gives U-boats Biscay ports. Monthly sinkings climb above 300,000 tons.
- May 1941
Capture of U-110
HMS Bulldog seizes an intact Enigma machine — a priceless intelligence coup.
- Jan 1942
Operation Drumbeat
U-boats hit the unprepared U.S. east coast.
- Mar 1943
The crisis month
108 ships lost — Dönitz comes closest to winning.
- May 1943
"Black May"
41 U-boats lost in a single month. Dönitz withdraws. The tide turns.
- May 1945
Surrender
Dönitz orders U-boats to surface and surrender.
Across the three theatres, roughly 105,000 Allied sailors — naval and merchant — did not come home. They are remembered on stone panels at Tower Hill, Portsmouth, Washington, Laboe, and Kure — where the sea gives up no bodies and leaves only statistics.