Holmes's excellent study further burnishes Roosevelt's reputation, emphasizing his nuanced diplomacy over his warmongering and admiration for imperialism. Holmes argues that in most cases Roosevelt did not rush to interfere with the affairs of foreign countries, even within the immediate American sphere of interest, but instead developed a studied and largely consistent approach to international problems.

To Holmes, Roosevelt demonstrated a virtuous combination of idealism and muscular realism in both his domestic and foreign policymaking. In particular he developed the notion of “police power” during his tenure as New York police commissioner and then governor of New York, focussing on the need to prevent disorder in labour relations. This was then carried over to the presidency from 1901, following William McKinley's assassination. Roosevelt's notion of “international police power” reached its apogee in his December 1904 message to Congress, the famous “Roosevelt Corollary” to the Monroe Doctrine (3), after his successful negotiations on the state of finances in the American republic of Santa Domingo (amid fears of European intervention in contravention of the Monroe Doctrine) and his triumphant election as President in his own right.

One of the strengths of Holmes's book is its blending with historical examples of Roosevelt's political philosophy and views on international relations. Chapter 8 details six case studies to illustrate the argument: interventions in Cuba, the Philippines, the Panama Canal area and Santa Domingo, and attempts to deal with threats from European powers in Venezuela in 1902–3 and Morocco, the latter culminating in the Algeciras conference of 1906. It is to Holmes's credit that he includes such a wide array of examples. Although he has to acknowledge that at times, especially in the case of Panama, Roosevelt's actions showed a “breach of self-restraint” (228), he traces the evolution of Roosevelt's ideas as he grappled with the intricacies of affairs within the Americas and, increasingly, the affairs of the Great Powers.

As Holmes notes, however, Roosevelt himself was not inclined to write at length about the nature of this police power and it therefore remains open to interpretation. Yet Holmes skilfully teases out a set of guiding principles that kept the US out of war, with the obvious exception of the Philippines where it was already fighting, and even saw attempts to prevent Great Power rivalry from spilling over into a major conflict. As the author ultimately states (236), Roosevelt's ideas about international police power are more useful as an analytical tool than as a direct template for twenty-first-century diplomacy, but this study of them offers modern policymakers much food for thought.