Alexander von Benckendorff was born into the Baltic German noble Benckendorff family in Reval (Tallinn in present-day Estonia), son of General Baron Christoph von Benckendorff [de] (12 January 1749, Friedrichsham – 10 June 1823, Kolga), who served as the military governor of Livonia, and of his wife Baroness Anna Juliane Charlotte Schilling von Canstatt (31 July 1744, Thalheim – 11 March 1797, Riga), who held a high position at the Romanov court as senior lady-in-waiting and best friend of Empress Maria Fyodorovna (the second wife of the Emperor Paul).

Having received his education at a Jesuit boarding school, Benckendorff started military service in 1798 in the Semyonovsky Life-Guards Regiment.

After British and Prussian forces arrived to succeed him, his unit proceeded to take Louvain and Mechelen, liberating 300 imprisoned Englishmen captured in Spain.

[9] (At the end of March the French surrendered, which was followed by Treaty of Fontainebleau (1814)) In 1821 he attempted to warn Emperor Alexander I of the threat from the Decembrist clandestine organisation, but the Tsar ignored his note.

After the 1825 Decembrist Revolt he sat on the investigation committee and lobbied for the establishment of a Corps of Gendarmes and of a secret police, the Third Section of the Imperial Chancellery.

His aim for Russian historiography was reflected in his statement that "Russia's past was admirable, its present is more than magnificent and as for its future — it is beyond anything that the boldest mind can imagine.

[citation needed] In 1817 Alexander von Benckendorff married Elisaveta Andreyevna Donets-Zacharzhevskaya (11 September 1788 – Berlin, 7 December 1857).

The couple had three daughters: A recent Russian publication reveals his own view of his early life: Zapiski Benkendorfa: Otechestvennaia voina; 1813 god: Osvobozhdenie Niderlandov (Benkendorff's Notes.

This book reproduces two sections of Benckendorff's private notes that had not seen publication since 1903, very lively on the events of the Napoleonic war, correspondences with his contemporaries, Bagration and others, and associated regimental histories.