The foreign regiment first participated to the pacification of Algeria, then was funneled to the Crimean War () where the regiment formed a brigade with the foreign brother regiment, 2nd Foreign Regiment 2e RE, at the corps of the 6th Division. The regiment participated to the Battle of Alma () and to the Siege of Sevastopol (). The regimental commander, colonel Vienot was killed in combat on May 1, 1855. The regiment participated to the apprehension of the Malakoff tower on September 8, 1855. The regiment then partcipiated to the Italian campaign () in 1859, at the corps of the 2nd Infantry Division of the 2nd Army Corps of Patrice de MacMahon, Duke of Magenta, and illustrated capability during the Battle of Magenta (). The regiment entered triumphantly in Milan liberated on June 7, 1859.