The 9th German U-boat Flotilla (German 9. Unterseebootsflottille) was formed in October 1941 in Brest. It became operational in April 1942, after the first combat ready U-boat, U-213, reached the Brest base on 20 March 1942. The flotilla operated mostly various marks of the Type VII U-boat and it concentrated its efforts mainly in the North Atlantic, against convoys to and from Great Britain.
The symbol of the 9th Flotilla, Der lachende Schwertfisch or the "laughing Swordfish" became the unit symbol after Lehmann-Willenbrock assumed command. It has previously been the conning tower emblem on his previous command, U-96 of "Das Boot" fame.