At the outbreak of World War I, the Gold Coast of Long Island was home to the most concentrated combination of financial, political and social clout in the country. Bankers, movie producers, society glitterati, government officials and an ex-president mobilized to arrange massive loans, send supplies and advocate for the Allied cause. The efforts undercut the Wilson administration’s official policy of neutrality and set the country on a course to war with Germany. Members of the activist families–including Morgans, Davisons, Phippses, Martins, Hitchcocks, Stimsons and Roosevelts–served in key positions or fought at the front. Historian Richard F. Welch reveals how a potent combination of ethno-sociological solidarity, clear-eyed geopolitical calculation and financial self-interest inspired the North Shore elite to pressure the nation into war.