Alvensleben was born on 19 May 1902, in
Wittenmoor (now part of
Stendal) to Ludolf Udo von Alvensleben (1852–1923) and Ida, née von Glasenapp (1866–1924). He was taught in various convent schools at
Magdeburg in
Brandenburg an der Havel and passed his
Abitur in 1921 at the Klosterschule
Roßleben. After four years of practical training he commenced studies in agriculture, forestry, and law in
Eberswalde and
Munich. In 1927, Alvensleben married Cora von Erxleben and started to work at his wife's country estates at Tankow-Seegenfelde in the district of
Friedeberg, then in the
Province of Brandenburg, part of the German
Free State of Prussia, and at Dertzow in the district of
Soldin,
New March, also in the province of Brandenburg, in 1929. In 1936, he bought the forested estate of Viarthlum, in the district of
Rummelsburg, in the Free State
Province of Pomerania. All were in areas transferred to
Poland by the
Potsdam Agreement in August 1945 following the end of World War II. Alvensleben had two daughters, born in 1934 and 1936. A deeply religious
Christian, he had become by then a Knight of Justice of the
Order of Saint John. ==Military service==