 Complete the following phrase:  Attached to 6th U-boat Flotilla based at Kiel, U-655 completed her training period on 1 March 1942 and was assigned to front-line service, The submarine left Kiel on 11 March reaching Helgoland on 12 March. From there the submarine departed on the 15 March on her first operational patrol to form part of the Ziethen wolfpack consisting of U-655 plus U-209, U-376 and U-378 operating northwest of Tromso in the Norwegian and Barent seas against the homebound 