Tide-predicting Machine
The tide-predicting machine was a little bigger than many of these other inventions, but in terms of the size to impact ratio, it fits in well with little inventions. Tide-predicting machines were essentially complex analog calculators. These had been in use for some time, having been first developed in the 1870s, and were treated as classified technology by the time of the second World War.
The US No.2 Tide Predicting Machine, called “Old Brass Brains” was essential to Allied operations in World War II. “Old Brass Brains” relied on a system of gears, pulleys and chains to complete the complex equations necessary to predict the tides at specific locations. This machine predicted the tides for all island landings in the Pacific, as well as for the essential landing in Normandy on D-Day. The landings in Normandy provide the best example of the importance of the tide-predicting machine; however, US No. 2 Tide Predicting Machine remained in use until it was replaced by a computer in 1965.
German Field Marshall Erwin Rommel expected Allied forces to storm Normandy at high tide. In preparation for the attack, he installed barriers of wood, cement and steel, designed to stop ships and landing parties from reaching the shores of Normandy. The Allies would have to plan to land at low tide, destroy the barriers to open channels inland, and get ships off the beach before becoming stranded. This made the timing of the landing essential.
In addition, the ships had to be able to cross the English Channel at night, have enough daylight for a naval assault prior to the landing, and needed a late-rising moon to allow paratroopers to drop into Normandy overnight the previous night. Only three dates in June met all of these requirements, according to the tide-predicting machine; June 5, 6 and 7.
The carefully planned assault helped to turn the tide of war, forcing the Germans to fight on two fronts. By the end of June 1944, more than a million troops had landed in Normandy and Victory Europe Day or VE Day was less than a year away.