Submarine Operational Effectiveness in the 20th Century: Part One (1900 - 1939)

A very new weapons system, the lurking submarine with its self-propelled torpedoes fired from ambush changed the complexion of naval warfare forever. Both warships and merchant ships were at risk. In 1914 U-boats demonstrated their capability to sink major warships.

During 1915 they turned their attention to merchant ships and began to sink or capture them in wholesale lots. U-boats nearly won the First World War for Germany by forcing Great Britain into peace negotiations in late 1917. U-...