The U-boat was laid down on 20 January 1940 at the Schichau-Werke yard, Danzig, launched on 15 March 1941, and commissioned on 21 June 1941, Kapitänleutnant Wolfgang Heyda commanding.[1]
U-434 sailed from Kristiansand, Norway on 2 November 1941, on her only war patrol. On 18 December, U-434 was sunk in the North Atlantic north of Madeira, Portugal, in position 36.25°N -63°W. The U-boat was forced to the surface by depth charges from the British escort destroyer and the destroyer . There were two dead and 42 survivors.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-434 had a displacement of 769t when at the surface and 871t while submerged. She had a total length of 67.1m (220.1feet), a pressure hull length of 50.5m (165.7feet), a beam of 6.2m (20.3feet), a height of 9.6m (31.5feet), and a draught of 4.74m (15.55feet). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of NaNPS for use while surfaced, two AEG GU 460/8-276 double-acting electric motors producing a total of 750PS for use while submerged. She had two shafts and two 1.23abbr=onNaNabbr=on propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-434 was fitted with five 53.30NaN0 torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.82NaN2 SK C/35 naval gun, 220 rounds, and a 2sp=usNaNsp=us C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
U-434 took part in two wolfpacks, namely: