The first three pages of the Prologue are a synopsis of the process of President Donald Trump interviewing and then approving Mattis for the Cabinet-level position of secretary of defense in 2016. This experience bookends Call Sign Chaos as the last chapter ends with Mattis walking into his office prepared to begin his duties as a Cabinet member.

The remainder of the Prologue lays out Mattis’s explicit motivations for writing this memoir. Mattis puts it succinctly: “My purpose in writing this book is to convey the lessons I learned for those who might benefit, whether in the military or in civilian life” (xiii). These lessons, Mattis relates, mattered immensely in his life as the choices he made often dictated whether people under his command would be risking their lives for a larger purpose.

Call Sign Chaos opens with a cursory glance at Mattis’s youth. His parents are mentioned only in passing. His father was a sailor, and his mother worked for the army in World War II. They give Mattis significant freedom as a young man, allowing him to hitchhike around as young as 13. The Mattis family lives in the Pacific Northwest, and he does a good deal of hiking and camping.