While at Harvard, Roosevelt began a systematic study of the role played by the nascent US Navy in the War of 1812, largely completing two chapters of a book he would publish after graduation.
He would later recall that in the middle of Mathematics classes at Harvard, his mind would wander from his lessons to the accomplishments of the infant US Navy. Reading through literature on the subject, Roosevelt found both American and British accounts heavily biased and that there had been no systematic study of the tactics employed in the war. Although a challenge for a young man with no formal military or naval education, but helped in part by his two former Confederate naval officer Bulloch uncles, he did his own research using original source materials and official US Navy records. Unlike previous American and British books that ignored quantifiable facts to push a specific agenda, Roosevelt's carefully researched book was akin to today's modern doctoral dissertations, complete with carefully researched drawings depicting individual and combined ship maneuvers, charts depicting the differences in iron throw weights of cannon shot between American and British forces, and analyses of the differences between British and American leadership down to the ship-to-ship level. It is today considered one of the first modern American historical works. Published after Roosevelt's graduation from Harvard, "The Naval War of 1812" was immediately accepted by reviewers who praised the book’s scholarship and style. The newly established Naval War College adopted it for study, and the Department of the Navy ordered a copy placed in the libraries of every capital ship in the Fleet. This book would help establish Roosevelt's reputation as a serious historian. Roosevelt brought out a subsequent edition including questions and answers from both scholars and critics. One modern naval historian wrote: "Roosevelt’s study of the War of 1812 influenced all subsequent scholarship on the naval aspects of the War of 1812 and continues to be reprinted. More than a classic, it remains, after 120 years, a standard study of the war."