The pass was fortified in the 16th century by the Habsburgs in fear of French invasion, which however would not occur until the Peninsular War and the arrival of Napoleon's general Louis Gabriel Suchet in 1808. He was later followed by Colonel Leonard Morin who records in his Memoirs of the 5th Regiment (1812–13) both the danger of the pass and the horrible existence of the population of Canfranc. The French would leave by the same road after their defeat by General Francisco Espoz y Mina in 1814.