The film shows how Italy's historic national hero Giuseppe Garibaldi (embodied by Renzo Ricci) leads a military campaign known as Expedition of the Thousand in 1860 and conquers Sicily and Naples. When the Bourbon monarchy has left Southern Italy, he supports Victor Emmanuel II of Italy who achieves a lasting unification under the aegis the House of Savoy.
Roberto Rossellini stated he was very more proud of this film than of any other film he ever made.