Ardennes 1944 by Antony Beevor
This deeply researched work give a definitive account of the Battle of the Bulge, the battle involving more than one million men that finally broke the back of the Wehrmacht.
Dead Wake by Erik Larson
This is the story of the last crossing of the Lusitania the infamous luxury cruise liner that was sunk by a German U-boat at the beginning of WWI.
The Secret War by Max Hastings
This is the story of how spies, codes, guerillas and espionage influenced the course of WWII.