In 1941, construction of the DORA 1 submarine base started in Trondheim. Two years later, in June 1943, it was handed over to the flotilla commander, "Korvettenkapitän" (later "Fregattenkapitän") Rolf Rüggeberg. The 13th submarine flotilla was a front line unit, and a total of 55 Type VIIC and &lt;a href="German%20Type%20VII%20submarine%23Type%20VIIC.2F41"&gt;VIIC/41&lt;/a&gt; served with it until the end of the war in May 1945.