The tide predictions for D-Day | Physics Today | AIP Publishing  Arthur Thomas Doodson was a very talented Mathematician and Statistician whose in-depth expertise in calculating the tides provided the D-Day military planners with the knowledge of the correct tidal conditions for the costal landings at Normandy.  He had suffered much humiliation as a Conscientious Objector in WW1. 

Doodson was a leading man in the Needed Truth overseers of his day, and very respected. He was very kind to younger brethren and wrote a small book on N.T. Principles, "The Search for the Truth of God" (1947). 

A simplified account of Arthur T Doodson's achievement. D-Day: How a British Oceanographer's Invention Decided Normandy's Fate (inverse.com)