Wolfpacks ( were employed by Nazi Germany's Kriegsmarine during World War II against Allied and neutral shipping. They were also used later in the Pacific War by the United States against Japanese shipping.
Outbreak of War From the outbreak of war until mid-1940 there were various groups of U-boats engaged in collective patrols. With the exception of the experimental, Hartmann's wolfpack, in 1939, the first recognised wolfpack was led by Günther Prien in June 1940.
Invasion of Norway and Denmark In preparation for the invasion of Norway and Denmark, in early April 1940, 31 U-boats were readied for operations between England and Norway. On 6 April, the codeword was transmitted and German submarines began their operations.
List of Wolfpacks