This book has been released under the following alternate titles:-
Go in and Sink!
1943: Europe is wracked by the fiercest fighting of the Second World War. Lieutenant-Commander Steven Marshall brings his submarine, sole survivor of a flotilla decimated in Mediterranean waters, back to Britain. There he assumes command of a captured German U-boat and returns to the Mediterranean, to pose as a German ship and crew. The Royal Navy is unaware of the spy ship's true identity and suspense builds to unbearable levels as Commander Marshall threads his way among potential destroyers on both sides, to annihilate enemy installations and to sabotage an Italian factory at work on secret weapons threatening the Allied invasion.
Author: Douglas Reeman
Title: His Majesty's U-Boat
First Published by: Putnam Pub Group
Date: January 1973