Photo of British Army officer General Sir John Greer Dill (1881-1944), Chief of the Imperial General Staff, studies a globe in his office in London during World War II in January 1941.

Then General Sir John Dill poses for a contemplative portrait in January 1941. In his wartime role as senior British member of the Combined Chiefs of Staff he provided back channel information vital to a coordinated Allied war effort. (Reuben Saidman/Popperfoto (Getty Images))

Reuben Saidman/Popperfoto (Getty Images)