For the study of international relations, knowledge of the history of western cooperation in the 20th century is essential. The third volume in the series Footprint of the 20th Century reviews the broader history from America's entry in the First World War in 1917 and the start of the American Era in international relations one hundred years ago, to the inauguration of President Trump in 2017. This volume deals with the American era in world politics, characterised by the creation of such international institutions as the League of Nations, the United Nations, ILO, IBRD, IMF and UNESCO. Developments are examined in a circumscribed period-from the outbreak of the First World War in July 1914 to the celebration of NATO's Sixtieth Anniversary on April 4, 2009. This book is reprinted with a new epilogue that covers this period up until the inauguration of Donald Trump as President of the United States in January 2017. This reprint is now part of Footprints of the 20th Century-Third Edition series. (Series: Footprints of the Twentieth Century, Vol. 3) Subject: Legal History, International Relations]