Alan Mathison Turing was a British mathematician, logician, cryptanalyst, philosopher, pioneering computer scientist, mathematical biologist, and marathon and ultra distance runner. He also one an OBE. He was born in Paddington London on the 23 June 1912 and died in Wilmslow in Cheshire on the 7 June 1954.
What did he do?
Alan Turing broke the Enigma. The Enigma machine was a bit like a type writer except that each letter pressed could generate 150,000,000,000,000,000,000 options. This machine stored all the information about Germany's plans. When Turing broke the code, it informed the British of the great sea battles that Germany were planning. Because Turing broke the code, we knew about the D-Day landings so we could prepare for it.
This is the machine that the Germans used to communicate without being detected. Until Turing invented this...
It Broke the code by making the Turing Bomb. This is a picture of the Turing bomb.
Alan Turing - Celebrating the life of a genius