Iako je Aecijus uspio vjeriti svoga sina Gaudentijusa sa Valentinijanovom kćerkom Placidijom 453., Valentinijan je se plašio Aecijusa, jer je mislio da Aecijus želi postaviti svoga sina na carsko prijestolje. Rimski senator [[Petronius Maximus]] i upravnik Heraclius su zato uspjeli nagovoriti Valentinijana da izvrši atentat na Aecijusa. [[21. septembar|21. septembra]] [[454]]. je Valentinijan svojom rukom ubio Aecijusa.
Although in 453 Aëtius had been able to betroth his son Gaudentius to Valentinian's daughter Placidia, Valentinian felt intimidated by Aetius, who had once supported Joannes against him and whom Valentinian believed wanted to place his son upon the imperial throne. The Roman senator [[Petronius Maximus]] and the chamberlain Heraclius were therefore able to enlist Valentinian in a plot to assassinate Aëtius. On [[September 21]], [[454]], when at court in [[Ravenna]] delivering a financial account, Aëtius was slain by Valentinian's own hand. [[Edward Gibbon]] credits [[Sidonius Apollinaris]] with the famous observation, "I am ignorant, sir, of your motives or provocations; I only know that you have acted like a man who has cut off his right hand with his left" (''Decline and Fall of the Roman Empire'', ch. 35).
MaximusOčekivalo expectedse toda beMaximus madepostane patricianpatricije inumjesto place of AëtiusAecijusa, butali wasje blockedto byspriječio Heraclius. Tražeći Seeking revengeosvetu, Maximus arrangedje withdogovorio twosa Hundva friendsAecijusova ofhunska Aëtiusprijatelja, OptilaOptilom andi ThraustilaThraustilom, toda assassinatese bothizvrši Valentinianatentat IIIna andValentinijana HeracliusIII. i Heracliusa. On [[March16. 16mart]],a [[455]]., Optila stabbedje theubo emperorcara inu thehramu templedok asje hesilazio dismountedsa inkonja theu Campuskampu Martius andi preparedspremao forse a sessionza ofvježbe archerygađanja practicestrijelom. Dok Asse theiznenađeni stunnedcar emperorokretao turnedda tovidi seeko whomu hadje struckzabio himnož, Optila finishedje himzavršio offposao withs anotherjoš thrustjednim ofubodom his bladeoštrice. U Meanwhile,međuvremenu je Thraustila steppedubio forward and killed HeracliusHeracliusa. Mnogi Mostvojnici, ofkoji thesu soldiersbili standingu closesamoj byblizini haddogađaja, beensu faithfulbili followersvjerni ofAecijusovi Aetiuspratioci andi nonenisu liftedpomakli ani hand toprsta saveprilikom theubistva emperorcara.
