Having received his education at a Jesuit boarding school, Benckendorff started military service in 1798 in the Semyonovsky Life-Guards Regiment. During Napoleon's invasion of Russia in 1812, Benckendorff led the Velizh offensive, taking three French generals prisoner. When Moscow was liberated (October 1812), he became the commander of its garrison. In the foreign campaigns following, he defeated a French contingent at Tempelberg and became one of the first Russians to enter Berlin. He further distinguished himself at Leipzig (October 1813) and later cleared out the French forces occupying the Netherlands. After British and Prussian forces arrived to succeed him, his unit proceeded to take Louvain and Mechelen, liberating 600 imprisoned Englishmen on the way.