During that time she carried out ten war patrols, but had to return to port following damage after colliding with U-631 in the North Atlantic on 17 April 1943.

[1] U-71's early history was fairly typical of many boats in the U-Boot-Waffe (U-boat arm); she began her operational life in Kiel, but soon moved to St. Nazaire in France, where despite being nearer to the main hunting grounds of the Atlantic, failed to take advantage of her more advanced location.

Her luck and that of her commander, Kapitänleutnant Walter Flachenberg, changed on her fifth foray, sinking a total of 38,894 GRT of shipping in March and April 1942.

Under a new skipper, Hardo Rodler von Roithberg, the boat could not reproduce the form of her fifth patrol, despite sortieing three times between July 1942 and February 1943.

By now the writing was on the wall for Germany's U-boats; U-71 was only one submarine that departed La Rochelle and after another unsuccessful voyage, steamed to Königsberg (on the Baltic coast), arriving in May 1943.