) ▁was ▁a ▁German ▁prince ▁of ▁the ▁House ▁of ▁As can ia . ▁ ▁He ▁was ▁a ▁r uler ▁of ▁the ▁Princi p ality ▁of ▁An halt - D orn burg , ▁then , ▁from ▁ 1 7 4 2 , ▁a ▁r uler ▁of ▁the ▁entire ▁Princi p ality ▁of ▁An halt - Z er bst . ▁He ▁was ▁also ▁a ▁Pr uss ian ▁Gener alf eld mar sch all , ▁but ▁is ▁best ▁known ▁for ▁being ▁the ▁father ▁of ▁Catherine ▁the ▁Great ▁of ▁Russia . ▁ ▁Life ▁Christian ▁August ▁was ▁the ▁third ▁son ▁of ▁John ▁Louis ▁I , ▁Prince ▁of ▁An halt - D orn burg ▁and ▁Christ ine ▁Ele on ore ▁of ▁Ze utsch . ▁After ▁the ▁death ▁of ▁his ▁father ▁in ▁ 1 7 0 4 , ▁Christian ▁August ▁inherited ▁An halt - D orn burg ▁joint ly ▁with ▁his ▁brothers ▁John ▁Louis ▁II , ▁John ▁August us ▁( d ied ▁ 1 7 0 9 ), ▁Christian ▁Louis ▁( d ied ▁ 1 7 1 0 ) ▁and ▁John ▁Frederick ▁( d ied ▁ 1 7 4 2 ). ▁ ▁After ▁possibly ▁six ▁months ▁as ▁a ▁captain ▁in ▁the ▁regiment ▁guard ▁in ▁ 1 7 0 8 , ▁on ▁ 1 1 ▁February ▁ 1 7 0 9 ▁he ▁joined ▁the ▁Regiment ▁on ▁foot ▁in ▁An halt - Z er bst ▁( No . ▁ 8 ) ▁which ▁later ▁changed ▁its ▁name ▁to ▁the ▁Gren ad ier ' s ▁Regiment ▁King ▁Frederick ▁William ▁IV ▁of ▁Pr uss ia