Encyclopedia Britannica D-Day: The Turning Point of WWII The Invasion that Changed History Forever Product Information Despite Allied gains in the period leading up to theinvasion, Hitler still had a stranglehold on Europe that only a major assault onthe Continent could reverse. Learn the historical and military context of theD-Day invasion and why so much was at stake. Leaders and Generals -Eisenhower. Montgomery. Marshall. Patton. The D-Da