The French diplomat, Charles-Irénée Castel de Saint-Pierre, who worked negotiating the Treaty of Utrecht at the end of the War of Spanish Succession proposed, through "Perpetual Union", "an everlasting peace in Europe", a project taken up by Jean-Jacques Rousseau, and Immanuel Kant after him. After the Napoleonic Wars and the Revolutions of 1848 in the 19th century, Victor Hugo at the International Peace Congress in 1849 envisioned a day when there would be a "United States of America and the United States of Europe face to face, reaching out for each other across the seas". World War I devastated Europe's society and economy, and the Versailles Treaty failed to establish a workable international system in the League of Nations, any European integration, and imposed punishing terms of reparation payments for the losing countries. After another economic collapse and the rise of fascism led to a Second World War, European civil society was determined to create a lasting union to guarantee world peace through economic, social and political integration.