Overlooked, forgotten, misunderstood: the "other" SIGINT in World War II

Abstract

Fascination with ULTRA, the extraordinary World War II cryptologic intelligence, by historians and the public alike has eclipsed knowledge of and study of a second important cryptologic intelligence source. Whereas ULTRA provided senior Allied leaders with deep insight into enemy strategic thinking and plans, tactical cryptologic intelligence often gave combat commanders the vital information needed to win actual battles. Tactical cryptologic intelligence is less known and studied partly because it is in the shadow of ULTRA. In addition, fewer sources about the practice of tactical cryptologic intelligence have survived, and those readily available are fragmented and anecdotal. Tactical cryptologic intelligence merits further research and analysis if we are to have a fuller understanding of cryptology in practice and intelligence in the world war.