Kirchheim entered the Imperial Army as an officer candidate on May 1, 1899. He became a Leutnant with the Infanterie-Regiment Prinz Friedrich der Niederlande (2. Westfälisches) Nr. 15 in Minden on October 18, 1900. On October 1, 1904, he transferred to the Schutztruppe of German Southwest Africa, going on an eight-year tour of duty in the colony. In January 1904, the native Herero tribe of Southwest Africa rebelled against German colonial rule over the expropriation of their land and cattle. Later in the year, the Nama/Hottentot tribe also took up arms against their colonial rulers, beginning the Herero Wars. Generalleutnant Lothar von Trotha, the Military Commander of German Southwest Africa, suppressed the rebellion with extreme brutality, Relying on a policy of ethnic cleansing backed by forced labor, deportations, wholesale execution of prisoners and the use of concentration camps. The Germans crushed the rebellion by early 1907 and by 1908 they re-established authority over the territory. Heinrich won the Order of the Crown (Prussia) 4th Class with Swords for his actions against fighting the rebelling African tribes. However, only 6 years later World War I began and the fighting would spread to Africa. In September 1914 British and South Africa troops invaded the colony and by July 1915 they had conquered the territory.