Alternative History
Unterseeboot 20U-20
Service War Ensign of Germany (1938–1945) Kriegsmarine
Class Type-IIB U-boat
Launched 14 January 1936
Commissioned 1 February 1937

Unterseeboot 20, or more commonly U-20 was a German Type IIB U-boat of the Kriegsmarine. She was commissioned on February 1, 1936. During the , she conducted operations against enemy ships. She famously sunk of the coast of the Netherlands, the first loss of life in the war.