The book is based on detailed research in Brazilian, British, American, and French archives, and on numerous interviews with surviving military and civilian leaders. It also makes extensive use of hitherto unused internal army documents, as well as of private correspondence and diaries. It is thus able to shed new light on the army’s personnel and ethos, on its ties with civilian elites, on the consequences of military professionalization, and on how the army reinvented itself after the collapse of its command structure in the crisis of 1930—a reinvention that allowed the army to become the backbone of the post-1937 dictatorship of Getulio Vargas.