Alexander Samsonov was born in in Kherson Oblast on 2nd November 1858. After being educated at the Vladimir of Kiev Cadet Corps and elite Nikolaev Cavalry School. In 1876 he joined the Imperial Russian Army. Samsonov fought in the Russo-Turkish War and afterwards he attended the Nikolaevsky Military Academy in St. Petersburg.
On November 4, 1888 he was appointed senior aide to the staff of the 20th Infantry Division, and from July, 1885 to February, 1889 served as Senior Staff Adjutant to the Caucasus Grenadier Division. Samsonov eventually became commandant of the Elisavetgrad Cavalry School.
Samsonov commanded a Cossack cavalry unit during the Boxer Rebellion in 1900 and the Russo-Japanese War (1904–1905). In 1906, Samsonov became Chief of staff of the Warsaw Military District, and in 1909 was Governor-General of Turkestan. He was also commander of the Semirechye Cossacks.
On the outbreak of the First World War Samsonov was given control of the Second Army for the invasion of East Prussia. Disadvantaged by poor communications and a shortage of supplies, Samsonov's forces were surrounded and destroyed at Tannenberg in August. The German Eighth Army killed or captured most of his troops. It is estimated that only 10,000 of the 150,000 Russian soldiers managed to escape the encirclement. Aware that he had made a terrible tactical error, Samsonov committed suicide on 29th August, 1914.