In World War II, German military tactics nerds were able to find an initial advantage. Fortunately, the rulers (Nazis) were fuzzy-headed populists who believed in mysticism and half-baked distortions of economic and scientific theories, so it wasn't the engineers who ruled -- it was still the jocks and popular kids. By the end of the war, it was the allies who had significant technical advantages in military hardware, sensing equipment, and cryptography.

EDIT: There were also many instances of higher-ups impeding technical advances that could have been decisive, like stealth bombers.