An eyewitness account of the fight for supremacy at sea during World War II, as told by a man who was in the thick of combat against Nazi Germany.   The Battle of the Atlantic was an unremitting assault by enemy boats and aircraft against Allied merchant ships that were the lifeline of Great Britain--and the vigilant defense against them made by the Royal Navy and other allied forces.   Captain Donald Macintyre--a winner of the Distinguished Service Cross who participated in the fighting, escorting over 1,100 ships and losing only two--tells the story with immediacy and clarity. He describes the measures employed to defeat the amazingly successful 'wolf-pack' tactics of the U-boats, the convoy system and individual convoys, never shirking from how desperately close to defeat the Allies were at times.   Not only does he analyze the strategic issues of the day, he also describes the battle from the viewpoint of the participants themselves. The long, drawn-out duels between escort and U-boat are made vivid by quotations from the log-books of some of the ablest escort-commanders as well as combat reports of the German U-boat captains.   Featuring dozens of rare wartime photographs drawn from both German and British sources, this account of the sacrifice and savagery of war makes the courage and endurance of those who fought in the Atlantic all the more palpable.