During the Third War of Independence in 1866, Campolongo saw the location of the last action between the Kingdoms of Italy and Austria. On July 26, a mixed Italian force of bersaglieri and cavalry defeated an Austrian force guarding the crossing of the Torre river and reached present-day Romans d'Isonzo in the Battle of Versa. This marked the maximum Italian advance into Friuli. Under the Treaty of Vienna (1866), Central Friuli (today's province of Udine) and western Friuli (today's province of Pordenone) were annexed by Italy together with Veneto after this war, while eastern Friuli (County of Gorizia and Gradisca, including Campolongo) remained under Austria. This division helped in part to give rise to “Italia irredenta”.