Having attended the "Gymnasium" in Danzig, Bronsart entered the Prussian Cadet Corps ("Kadettenanstalt") in Kulm and Berlin. On 28 April 1849 he joined the Berlin "Kaiser Franz Garde-Grenadier Regiment No.2" in the rank of lieutenant. From 1 June 1852 he served as adjutant in the 4th Guards Landwehr Regiment and attended the Prussian Military Academy from 1855 to 1858. On 1 May 1859 he was appointed to the German General Staff and achieved the rank of "Oberleutnant". Elevated to "Hauptmann" (Captain) on 23 February 1861; after three years of staff service he returned to regimental duty as a company commander in the II Army Corps, but was soon reappointed to the staff, and lectured at the Military Academy, becoming major in 1865 and lieutenant colonel in 1869.