Jerzy Rozycki was a Polish mathematician who, along with his colleagues Marian Adam Rejewski and Henryk Michal Zygalski, did amazingly valuable work decoding messages sent by the German Enigma machines. Although impossible to quantify, many lives must have been saved since, it is claimed, their work contributed to the shortening of World War II by between three to five years.
Find out more at: https://mathshistory.st-andrews.ac.uk/Biographies/Rozycki/