The German submarine weapon (German U-Bootwaffe) turned out to be the basic weapon of the Kriegsmarine during World War II. It is estimated that during its course the Germans launched about 1130 U-boats, of which they lost about 780 ships. However, this does not change the fact that the German U-boats were able to inflict huge losses on the Allied merchant shipping in the Atlantic. As in many other navies, including the Kriegsmarine, a considerable role was attached to the training of submarine crews. Mostly (especially before 1939) volunteers, most often between 17 and 25 years old, applied for service in the U-boats. After completing the basic training, the Kriegsmarine was assigned to one of the underwater weapons schools - the first such school was established at the end of 1933. After the victory in the September campaign, German practical training of submarines took place mainly in the Baltic Sea by school U-boat flotillas. The individual training of German U-boat officers was very demanding, which took place in a total of several centers and sometimes lasted almost a year. After passing it, another training took place, consisting in harmonizing the crews with officers and non-commissioned officers. It is worth adding that the basic armament of the German submarine forces during World War II were type VII and IX U-boats, and it was only at the end of the war that a truly revolutionary type XXI ship was introduced.
