German submarine U-870 was a Type IXC/40 U-boat of the Nazi German Kriegsmarine built for service during the Second World War. She was ordered on 25 August 1941, and laid down on 29 April 1943 at Bremen in Germany. She was launched on 29 October 1943 and commissioned on 3 February 1944. For her two patrols, she had one commander, Korvettenkapitän Ernst Hechler, who was awarded the Knight's Cross of the Iron Cross.