The Guardians is an ambitious work of institutional history with a global reach by a world-class historian at the height of her powers. It is a tour de force. The first comprehensive history of the League of Nations’ mandate system in a half-century, it does not relate events in each mandatory territory but at the international level, when arguments and conflicts spilled beyond the bounds of state and empire and came before the League, producing global effects. The book is beautifully produced, with well-chosen and placed images and appendices with useful information. The writing is engaging and often stunning; the argument subtle, yet clear and persuasive: the League’s Permanent Mandates Commission profoundly transformed the imperial order between the world wars, not by fulfilling its idealistic architects’ mission of making imperial rule more humane or uplifting but by creating a new apparatus for international oversight and a new level of “international diplomacy, publicity, and ‘talk”’ (4).

The book seeks to rehabilitate the League. Typically depicted as a failure for succumbing to the triple blows of the Manchuria Crisis, the Second Disarmament Conference, and the Italo-Ethiopia War, the League fared better, Pedersen argues, in other missions, particularly the mission to manage the imperial order through the mandates system. I must quarrel a little at the outset with Susan Pedersen’s claim that historians treat the mandate system dismissively. Few would argue that the effort to subject imperial rule to international control did nothing, though many might reasonably conclude that whatever profound effects it had were limited by critical geopolitical continuities. For this reason, few will need convincing about Pedersen’s broad argument that League oversight could not revolutionize the way mandates were governed but did oblige mandatory powers to “say they were governing them differently” (4). This argument goes down very easy. Where Pedersen is highly and importantly original, however, is in arguing that all that talk—having to legitimize their rule in Geneva before an international audience—made a substantive difference in the way history unfolded in particular places, making the League “an agent of geopolitical transformation” (5). Pedersen shows how the League “internationalized” particular conversations about mandated territories—how it displaced “certain political issues and functions . . . from the national or imperial, and into the international, realm” (5). Each member of the Permanent Mandates Commission, by using that body to its own ends, wound up strengthening the body’s authority. Politics was forced to speak the language of “textualism.” Well beyond the Commission itself, mandatory officials, legal scholars, humanitarians, and petitioners all spoke of the “spirit” and “letter” of the institutional texts they now had in common (65).