Conventional U-boat submarines had been the backbone of the Kriegsmarine during the early stages of World War 2. Still, as allies developed more prominent and more powerful fleets, the outdated German submarines drastically lost the battle. Karl Donitz, the supreme commander of the Kriegsmarine, knew that if they didn’t attain maritime supremacy in the Atlantic, Germany would lose the war: “Only a U-boat which no longer needed to surface in order to recharge batteries and which had both high speed and long endurance under water could improve our prospects in the battle ahead.” Donitz’s words were more than wishful thinking. By 1942, the unprecedented submarine he described was already being developed with the utmost urgency, and Hitler himself overviewed the development.The Type XXI Submarine became a Nazi wonder weapon developed in the latter stages of World War 2, one of only a few infamous Wunderwaffes actually built.It is also credited as the first real submarine in history, as previous U-boats were designed to submerge only during short periods and had to resurface constantly to recharge their batteries, making them easy targets for allied war efforts and considered mostly as submersible ships. In contrast, Type XXI was the first vessel in the world that could stay underwater indefinitely while reaching unparalleled depths, revolutionizing the way submarines were developed from then on.The submarine came in the heels of subsequent allied victories in the Atlantic, and Donitz hoped for a massive overturn based entirely on the deployment of the mighty Type XXI submarine. It was now a race against the clock and the only shot the Nazis had at winning the war…