Part 6/10:
The utility of Kelvin’s tide-predicting machines extended well into the 1960s, profoundly impacting military operations during World War II. The Allied invasion on D-Day exemplified the critical role played by tides in military strategy. Allied forces, aware of the German expectation for invasion at high tide, planned their assault to begin at low tide, a decision made possible through precise tidal predictions.
The battlefield also saw the emergence of innovative analog devices designed to counter aerial threats. The M9 Gun Director is a notable example; developed by Bell Labs, it employed op-amps and other analog circuitry to calculate ballistic trajectories for anti-aircraft weaponry effectively, drastically improving accuracy compared to earlier methodologies.