1. TIDE-PREDICTION MACHINE
Weather conditions, the moon and the tide were all crucial factors when planning the June 1944 invasion of north-west Europe. Air operations required clear skies and a full moon for good visibility, naval operations required calm seas, and ground troops needed to land at low tide, when German beach obstacles were exposed and easier to deactivate. D-Day required the best combination of all these factors and the Allies consulted a number of meteorologists and other experts when planning the invasion. In 1942, British mathematician Arthur Thomas Doodson had begun working on existing models of tide-prediction machines - essentially mechanised calculators that could reveal tidal patterns. In 1944, using his specially modified machine, Doodson identified the exact time the landings should take place (H-Hour) and that D-Day should fall between 5 and 7 June.
