"A new economic history which uncovers the forgotten left-wing, anti-imperial, pacifist origins of economic cosmopolitanism and free trade from the mid-nineteenth to the mid-twentieth century. The post-1945 international free-trade regime was established to foster a more integrated, prosperous, and peaceful world. As US Secretary of State Cordell Hull (1933-1944), "Father of the United Nations" and one of the regime's principal architects, explained in his memoirs, "unhampered trade dovetailed with peace; high tariffs, trade barriers, and unfair economic competition, with war." Remarkably, this same economic order is now under assault from the country most involved in its creation: the United States. A global economic nationalist resurgence - heralded by Donald Trump's "America First" protectionism and resultant trade wars with the USA's closest allies and trading partners - now looks to transform over seventy years of regional and global market integration into an illiberal economic order resembling that of the late nineteenth and early twentieth centuries. Economic cosmopolitan critics of today's retreat from free trade have offered dire warnings that doing so would be catastrophic for global consumers and an existential threat to regional and world peace. But under what circumstances did this ideological marriage of free trade, prosperity, and peace arise? Who were its main adherents? How did this same free-trade ideology succeed in becoming the new economic orthodoxy following the Second World War? And how might the successes and failures of this earlier struggle to reform the economic order inform today's globalization crisis? In Pax Economica, economic historian Marc-William Palen finds answers amid a century of transnational peace and anti-imperial activism that stretched from Britain's unilateral adoption of free trade in 1846 to the founding of the US-led liberal trading system that arose immediately after the Second World War. Over five thematic chapters, considering the period from different perspectives, and utilising archival research conducted in Europe, North America, and Australia, Palen shows that this politico-ideological struggle to create a more prosperous and peaceful world through free trade pitted economic cosmopolitans against economic nationalists. Cosmopolitans sought to counter the industrialising world's embrace of economic nationalism because they believed - much like today's critics of Trump's tariffs and Brexit - that economic nationalism laid the groundwork for trade wars, high prices for consumers, and geopolitical conflict; while free trade created market interdependence, prosperity, social justice, and a more peaceful world. Pax Economica argues that this cosmopolitan fight for free trade laid foundations for a century of anti-imperial and peace activism across the globe - and paved the way for today's global trade regime now under siege"--