He was "the toughest marshal" working the Indian Territory on behalf of Judge Isaac Parker, the real-life judge of the United States District Court for the Western District of Arkansas (having criminal jurisdiction in the Indian Territory, as the bailiff repeatedly announces in both films). When Cogburn goes to court in "Rooster Cogburn," it shows that Cogburn shot a total of 64 men in eight years, killing 60 (by the film's end, it was 70 shots, and 66 killed), all of whom he claimed to have killed in self-defense, in the line of duty, or fleeing justice.
He was married first to an Illinois woman who left him to return to her first husband after bearing Cogburn a single, extremely clumsy son, Horace, (of whom Cogburn says in, "He never liked me anyway"). Cogburn is described as a "fearless, one-eyed United States Marshal who never knew a dry day in his life."