Id have to say mine is the older WWII classics, Tora! Tora! Tora!, Midway, Sands of Iwo Jima, Patton etc.
The Great Escape
The Guns of Navarone
Alexander was a bad ass movie. Kingdom of Heaven was great as well, had some badass battle scenes in it.
Fat Man and Little Boy.
The scene with the criticality accident put chills in my spine, made me lose my breath, and made me cringe so hard and I even muttered out a "fu.......k...." through my teeth.
Ugh, just thinking of the tingling heat wave they would have felt...