Grounds For Truth

By A History Buff | Commentary, Grounds For Truth Substack On the anniversary of Midway, a veteran cryptanalyst explains why incomplete intelligence, used well, can change the course of war. I’ve spent enough years inside the grind of signals intelligence to know that intelligence victories rarely come from perfect decrypts. They come from fragments, traffic patterns, a sharp hunch backed by discipline and a commander willing to act while the picture is still fuzzy. Midway, fought June 4–7, 1942, is the textbook case. After Pearl Harbor the Japanese Navy’s operational code, JN-25, was still only partially recovered. It was a classic superenciphered system: a codebook with thousands of groups further masked by additive tables. Station Hypo, the Navy’s Combat Intelligence...