Carrel was born on 16 January 1829 in Valtournenche, in the Aosta Valley, an Arpitan-speaking village of Kingdom of Sardinia (now Italy) which lies at the foot of the Matterhorn. He served in the Bersaglieri, a light infantry unit of the Piedmontese army. He resigned from the Bersaglieri to work as a hunter and mountain guide, but was recalled to duty in 1859 to defend Italy against Austria in the Second Italian War of Independence, for which he won a French medal for the Italian campaign.