1 9 , ▁during ▁dem obil ization ▁of ▁the ▁American ▁Ex ped ition ary ▁Force , ▁Old s ▁was ▁assigned ▁to ▁the ▁staff ▁of ▁Col . ▁Frank ▁P . ▁L ah m , ▁chief ▁of ▁Air ▁Service , ▁Second ▁Army ▁at ▁Toul ▁as ▁flight ▁exam iner ▁( and ▁L ah m ' s ▁pilot ), ▁a ▁post ▁he ▁held ▁until ▁April ▁ 2 9 . ▁He ▁returned ▁to ▁Washington , ▁D . C . ▁in ▁August ▁ 1 9 1 9 . ▁ ▁Old s ▁transferred ▁to ▁Fort ▁R ug er ▁at ▁Hon ol ulu , ▁Hawai i , ▁in ▁October ▁ 1 9 1 9 , ▁as ▁Air ▁Service ▁Oper ations ▁Officer , ▁with ▁concurrent ▁command ▁of ▁the ▁ 3 rd ▁Bal lo on ▁Company . ▁A ▁reserve ▁officer , ▁he ▁decided ▁to ▁remain ▁in ▁the ▁military ▁but ▁needed ▁a ▁regular ▁commission ▁to ▁avoid ▁being ▁dem obil ized ▁by ▁the ▁National ▁Def ense ▁Act ▁of ▁ 1 9 2 0 , ▁which ▁reduced ▁the ▁Army ▁by ▁ 5 0 %. ▁Air ▁Service ▁command ers ▁in ▁Hawai i ▁submitted ▁three ▁letters ▁of ▁recommendation ▁on ▁his ▁beh alf , ▁he ▁passed ▁the ▁requ is ite ▁qual ifying ▁exam in ations , ▁and ▁on ▁July ▁ 1 , ▁ 1 9 2 0 , ▁when ▁the ▁law ▁took ▁effect , ▁Old s ▁received ▁comm issions ▁as ▁ 1 st ▁lieutenant ▁and ▁captain ▁of ▁Air ▁Service ▁of ▁the ▁Reg ular ▁Army . ▁ ▁In ▁July ▁ 1 9 2 1 ▁Old s ▁was ▁assigned ▁operations ▁officer