Following the devastation of the Thirty Years War, European powers began to seek treaties providing military assistance for allied countries. Over time such alliances became increasingly important, and scholars now debate whether, rather than acting as a deterrent, that they actually helped accelerate conflict at the beginning of both the First and Second World Wars. After 1945, fear of a similar doomsday scenarios occurring with such super alliances as NATO and its Soviet equivalent helped keep most confrontations regional throughout the Cold War. This new guide to international diplomacy examines 455 military alliances from the Peace of Westphalia to the present day. Each entry identifies the date, alliance members, type of agreement, and salient features of each treaty. In addition to summaries, substantial quotations are provided from many treaties, making the guide a collection of primary documents in addition to a quick reference tool. References are also made to where to find the full text of cited documents in consolidated treaty series. The scope is worldwide, but coverage emphasizes Europe and other developed nations. Alan Axelrod’s American Treaties and Alliances (CQ Press, 2000) provides complementary coverage to the major treaties of the United States. The arrangement is chronological with entries divided by century. Indexes list alliances by date, region, and title. An afterward explores the changing nature of military alliances. This set provides nearly double the coverage of the Encyclopedia of Historical Treaties and Alliances (Facts on File, 2006); however the latter provides longer quotations of the source materials. In addition, the lack of a general index that includes signatory nations and negotiators limits the research value of this set. Nonetheless, academic collections covering military and international affairs will find it a useful complement for their collections.