The Type XIV U-boat was a modification of the Type IXD, designed to resupply other U-boats. They were nicknamed "Milchkuh/Milchkühe (pl.)" (milk cows). Due to its large size, the Type XIV could resupply other boats with 432 t (425 long tons) of fuel, four torpedoes, and fresh food that was preserved in refrigerator units. In addition, the boats were equipped with bakeries, in order to provide the luxury of fresh bread for crews being resupplied. They had no torpedo tubes or deck guns, only anti-aircraft guns.
In 1942, the milk cows allowed the smaller Type VIIC boats to raid the American coast during the "Second Happy Time" of the Battle of the Atlantic. The milk cows were priority targets for Allied forces, as sinking one milk cow would effectively curtail the operations of several regular U-Boats and force them to return home for supplies. Ultra intercepts provided information concerning sailing and routing, and this, coupled with improved Allied radar and air coverage in the North Atlantic, eliminated most of them during 1943. By the end of the war all ten had been sunk. Milk cow duty was especially hazardous; 289 sailors were killed out of an estimated complement of 530–576 men.
U-459, commissioned 15 November 1941, scuttled 24 July 1943
U-460, commissioned 24 December 1941, sunk 4 October 1943
U-461, commissioned 30 January 1942, sunk 30 July 1943
U-462, commissioned 5 March 1942, sunk 30 July 1943
U-463, commissioned 2 April 1942, sunk 15 May 1943
U-464, commissioned 30 April 1942, scuttled 20 August 1942
U-487, commissioned 21 December 1942, sunk 13 July 1943
U-488, commissioned 1 February 1943, sunk 26 April 1944
U-489, commissioned 8 March 1943, sunk 4 August 1943
U-490, commissioned 27 March 1943, sunk 12 June 1944
Fourteen planned Type XIVs were cancelled. Three of them (U-491, U-492, U-493) were about 75% complete when work was stopped 1944. The other eleven boats had not been laid down when they were cancelled on 27 May 1944. On that same day Karl Dönitz stopped construction on the Type XX U-boats, large transport boats that would not have been ready until mid-1945.