With Blood and Iron — Douglas Reeman

January 1944: On the vast grey waters of the Atlantic, the balance of power has shifted. For Rudolf Steiger, ace U-boat commander, there is a new sense of urgency. Dedicated, ruthless, and fanatical, he has become a legend in his own time, a symbol of Germany's greatness. But now, as he takes the U-boat flotilla Meteor out into the bitter winter seas, he faces a new and deadly enemy -- his own nagging doubts about the outcome of the war. And Steiger is beginning to realize that his destiny may be to court a heroic death rather than suffer the shame of defeat.