▁loyal ty . ▁After ▁defe ating ▁O th o , ▁Vit elli us ▁dis band ed ▁the ▁Guard ▁and ▁established ▁a ▁new ▁Guard ▁six teen ▁coh ort s ▁strong . ▁V esp as ian ▁re lied ▁in ▁the ▁war ▁against ▁Vit elli us ▁upon ▁the ▁dis gr unt led ▁coh ort s ▁the ▁em peror ▁had ▁dismiss ed , ▁and ▁reduced ▁the ▁number ▁of ▁coh ort s ▁back ▁to ▁nine ▁upon ▁becoming ▁em peror ▁himself . ▁As ▁a ▁further ▁saf egu ard , ▁he ▁appointed ▁his ▁son , ▁Tit us , ▁as ▁Pra et or ian ▁pre fect . ▁ ▁While ▁the ▁guard ▁had ▁the ▁power ▁to ▁make ▁or ▁break ▁em per ors , ▁it ▁had ▁no ▁formal ▁role ▁in ▁government ▁administration , ▁unlike ▁the ▁personnel ▁of ▁the ▁palace , ▁the ▁Senate , ▁and ▁the ▁b ureau c racy . ▁O ften ▁after ▁an ▁out rage ous ▁act ▁of ▁violence , ▁reven ge ▁by ▁the ▁new ▁r uler ▁was ▁forth coming . ▁In ▁ 1 9 3 , ▁Did ius ▁Julian us ▁purchased ▁the ▁Empire ▁from ▁the ▁Guard ▁for ▁a ▁vast ▁sum , ▁when ▁the ▁Guard ▁au ction ed ▁it ▁off ▁after ▁killing ▁P ert ina x . ▁Later ▁that ▁year ▁Sept im ius ▁Sever us ▁march ed ▁into ▁Rome , ▁dis band ed ▁the ▁Guard ▁and ▁started ▁a ▁new ▁formation ▁from ▁his ▁own ▁P annon ian ▁leg ions . ▁Un r uly ▁mob s ▁in ▁Rome ▁often ▁fought ▁with ▁the ▁Pra et ori ans ▁in ▁Max imin us ▁Th ra x '