In the wake of the Revolutions of 1848 in Europe, democratic nationalism promoted the liberation of oppressed peoples from the shackles of absolutist empires and prophesied the emergence of a cosmopolitan brotherhood of nation states. From a global perspective, however, this political culture could be imperial. The governors of State of Buenos Aires modelled plans for the White colonization of the pampas on French Algeria. They sent a Military-Agricultural Legion to the enclave of Bahía Blanca, near the Patagonian frontier, to participate in the war against the Indians. Launched as the successor to Garibaldi’s Italian Legion of Montevideo, its leaders promised to bring civilization to savage lands in the spirit of Columbus and in the name of the Risorgimento. This case study offers a window into the cross-pollination of ideas concerning conquest and colonization between Latin America and Europe. Expansion and secession, empire and nation, mestizaje and racial hierarchies, cosmopolitanism and adventurism, all coexisted within an entangled republican universe.