Stimson was also the Secretary of War during WW2, which saw the creation and explosive growth of signals intelligence. As Secretary of War, he would have overse

Stimson was also the Secretary of War during WW2, which saw the creation and explosive growth of signals intelligence. As Secretary of War, he would have overseen the bulk of American signals intelligence and cryptanalysis, which let us view the Japanese and German thoughts in real-time and gave us an incredible advantage. ULTRA and related efforts saved convoy shipping across the Atlantic, gave the Allies North Africa, and won Midway (among many other victories). The irony is that he said "Gentlemen do not read each other's mail" as the Secretary of State, when he was made aware of the American Black Chamber. The Black Chamber was the one of the first "production line" signals intelligence units in the US government, and Stimson had it shut down due to his ethical concerns. This set the US at a signifigant disadvantage entering WW2, as we had to start on signals intelligence from scratch and learn a lot from the British (and what was left of the French and Polish signals intelligence units). It is telling that when it became truly necessary, these earlier ethical concerns were discarded in the face of military necessity.