The Cape Raider, by Justin Fox

An Allied-Nazi showdown in the icy South Atlantic
 
Jack Pembroke is thrust from a London desk job into the jaws of World War ii. As a young naval officer, he sees his ship sunk under him at Dunkirk, an event that leaves him defeated. After recovering in London, Jack sails for South Africa to join his admiral father at the Cape where a fledgling naval force is preparing to fight the coming onslaught of German raiders and u-boats in the South Atlantic. Jack is appointed commander of a small minesweeping flotilla – an inept bunch of South African sailors who distrust this foreign captain forced upon them – and must quickly mould them into a fighting unit.
 
Meanwhile a Nazi commerce raider, a powerful warship disguised as a neutral merchant ship, has left Germany for the Cape, intending to wreak havoc on Allied shipping. Jack and his flotilla will be pushed to the limit – and beyond.
 
A sweeping historical adventure, The Cape Raider is the tale of a broken hero who has to find himself despite the trauma of war, a domineering father and the death of his mother during the Blitz. He must adapt to a new country, a new navy and new love, and finally he must come face to face with the Nazi raider in a fight to the death in the icy seas off the southernmost tip of Africa.