Deciding when to storm the beach at Normandy was no easy feat, as the slightest variation in the tides could spell disaster for incoming boats. With a machine built by oceanographer Arthur Doodson, however, the British were able to predict the tides on Normandy's shores, thus deciding when D-Day would occur.

Deciding when to storm the beach at Normandy was no easy feat, as the slightest variation in the tides could spell disaster for incoming boats. With a machine built by oceanographer Arthur Doodson, however, the British were able to predict the tides on Normandy's shores, thus deciding when D-Day would occur.