▁Napoleon ▁III ▁Napoleon ▁III ▁and ▁Cav our ▁( P rem ier ▁to ▁Victor ▁Em manuel ) ▁agreed ▁to ▁war ▁on ▁Austria . ▁Following ▁the ▁Battle ▁of ▁Mag enta ▁( 4 ▁July ▁ 1 8 5 9 ) ▁the ▁Aust rian ▁forces ▁with d rew ▁from ▁the ▁Pap al ▁States , ▁precip it ating ▁their ▁loss ▁to ▁S ardin ia - P ied mont . ▁Revolution aries ▁in ▁Rom agna ▁called ▁upon ▁S ardin ia - P ied mont ▁for ▁an nex ation . ▁In ▁February ▁ 1 8 6 0 , ▁Victor ▁Em manuel ▁II ▁demanded ▁Um b ria ▁and ▁the ▁March es ; ▁when ▁his ▁demand ▁was ▁refused , ▁he ▁took ▁them ▁by ▁force . ▁ ▁Rel iance ▁on ▁French ▁and ▁Aust rian ▁soldiers ▁The ▁Pap al ▁States ▁were ▁coming ▁under ▁increased ▁pressure ▁from ▁anti - p ap al ▁national ists — not ably ▁Victor ▁Em manuel ▁II ▁of ▁S ardin ia - P ied mont ▁( l ater ▁king ▁of ▁Italy ). ▁The ▁Pope ▁was ▁obliged ▁to ▁rely ▁on ▁French ▁and ▁Aust rian ▁soldiers ▁to ▁maintain ▁order ▁and ▁protect ▁his ▁territ ories . ▁An ▁army ▁of ▁volunte ers ▁was ▁created ▁in ▁ 1 8 6 0 : ▁the ▁Pap al ▁zou aves ▁( zu avi ▁pont ific i ) ▁under ▁the ▁command ▁of ▁general ▁de ▁La ▁Mor ici ère . ▁They ▁came ▁from ▁different ▁countries ▁including ▁France , ▁Holland ▁( the ▁majority ), ▁Belg ium , ▁Canada ▁and ▁England . ▁Even ▁from ▁the ▁United ▁States ▁and ▁from ▁Italy ▁as ▁well .