From straightforward questions like "What does the 'D' in 'D-Day' stand for?" to the more difficult "Which Allied general was appointed 'Operational Commander for the Invasion Ground Forces?," this website offers 14 interactive quizzes, rated by difficulty, to test the knowledge of history buffs and students and even lets visitors create their own profiles, join teams and compete against one another.
See pictures of 13 battles that turned the tide at LIFE.com.