German submarine U-1228

German submarine U-1228 was a Type IXC/40 U-boat built for Nazi Germany's Kriegsmarine during World War II.

U-1228 was ordered in October 1941 from Deutsche Werft in Hamburg-Finkenwerder under the yard number 391. Her keel was laid down on 16 February 1943 and the U-boat was launched on 2 October. About three months later she was commissioned into service under the command of Oberleutnant zur See Friedrich-Wilhelm Marienfeld (Crew X/38) in the 31st U-boat Flotilla.

After work-up for deployment, U-1228 tranfered to the 2nd U-boat Flotilla and left Kiel for the West Atlantic on 5 September 1944 for her first and only patrol. Stopping briefly in Bergen, Norway, for replenishment, she experienced engine troubles in the Norwegian Sea and had to return to port. She set off again on 12 October from Bergen and operated south of Nova Scotia sinking one warship, HMCS Shawinigan (K136).

She returned to Bergen on 28 December 1944 and continued her journey to Flensburg the same day. On 17 January 1945, she arrived in Wesermünde where she spent the next two months in the yard. U-1228 set out again on 1 April 1945 for operations in the West Atlantic. After the surrender of Germany, the U-boat made for the closest Allied port and surrendered to US forces in Portsmouth, New Hampshire on 17 May 1945.

In August 1945 U-1228 was awarded to the United States and after being tested, she was sunk by USS Sirago (SS-485) on 5 February 1946 in position 42.53333°N, -69.61667°W.