▁L ally ▁from ▁se cur ing ▁India ▁for ▁France . ▁In ▁ 1 7 7 8 , ▁he ▁was ▁public ly ▁ex on er ated ▁by ▁Louis ▁XVI ▁of ▁his ▁alleg ed ▁crime . ▁ ▁Life ▁ ▁He ▁was ▁born ▁at ▁Rom ans - sur - Is ère , ▁D au ph iné , ▁the ▁son ▁of ▁Sir ▁Ger ald ▁L ally , ▁an ▁Irish ▁Jacob ite ▁from ▁Tu am , ▁County ▁Gal way , ▁who ▁married ▁a ▁French ▁lady ▁of ▁noble ▁family . ▁His ▁title ▁is ▁derived ▁from ▁the ▁L ally ' s ▁ancest ral ▁home , ▁Cast el ▁T ull end ally ▁in ▁Co . ▁Gal way , ▁where ▁the ▁L ally ' s ▁( origin ally ▁called ▁O ' M ull ally s ) ▁were ▁prominent ▁members ▁of ▁the ▁G ael ic ▁Arist ocracy ▁who ▁could ▁trace ▁their ▁ancest ry ▁back ▁to ▁the ▁second - century ▁High ▁King ▁of ▁Ireland , ▁Con n ▁of ▁the ▁H undred ▁Batt les . ▁ ▁Enter ing ▁the ▁French ▁army ▁in ▁ 1 7 2 1 , ▁he ▁served ▁in ▁the ▁war ▁of ▁ 1 7 3 4 ▁against ▁Austria ; ▁he ▁was ▁present ▁at ▁Det ting en ▁( 1 7 4 3 ), ▁and ▁commanded ▁the ▁regiment ▁de ▁L ally ▁in ▁the ▁famous ▁Irish ▁brig ade ▁at ▁Font eno y ▁( May ▁ 1 7 4 5 ). ▁He ▁was ▁made ▁a ▁brig ad ier ▁on ▁the ▁field ▁by ▁Louis ▁XV . ▁ ▁He ▁was ▁a ▁sta unch ▁Jacob ite ▁and ▁in ▁