Alvensleben joined the Prussian Army in 1821, serving in the Kaiser Alexander Guards Grenadiers Regiment No.

He went on to become the military governor of the Prussian Rhine Province and Westphalia in 1854, became a major-general in 1858, and the personal adjutant of King William I of Prussia in 1861.

In this position he signed the Alvensleben Convention with Russia to co-ordinate Russian and Prussian politics throughout the Polish January Uprising.

[2] Having served in the Royal headquarters in the Austro-Prussian War of 1866, Alvensleben led the peace negotiations with George V of Hanover.

In 1868 Alvensleben was promoted to General der Infanterie and commanded the IV Corps in the Battles of Beaumont and Sedan during the Franco-Prussian War.