Tactics of Mistake is a science fiction novel written by Gordon R. Dickson which was first published as a serial in Analog in 1970-1971. It is part of Dickson's Childe Cycle series, in which mankind has reached the stars and divided into specialized splinter groups. The fourth book written, it is chronologically the second book of the cycle, occurring roughly a century after Necromancer, and a century before Dorsai!. The primary character, Cletus Grahame, is the ancestor of the key characters in later works: the twins, Ian and Kensie Graeme, and their nephew, Donal Graeme. (The spelling of the last name was changed in intervening generations.)