Priscus Attalus was the first of several puppet emperors in the final lap of the Roman empire. He was a prominent Senator when Rome fell under Alaric's siege. In the wake of the pillaging that ensued, Alaric appointed him to the post in usurpation of Honorius whose court and castle was in Ravenna. While Honorius tentatively recognized Attalus as a colleague he wouldn't cave in to Alaric's demands for territory handover. Militarily unable to topple Honorius and unsatisfied with mere diplomatic recognition, Alaric seized what he could and left Rome with Attalus and Galla Placidia, Honorius's sister. Diplomatic activity continued between the two but Alaric died and negotiations continued under Ataulf, Alaric's brother-in-law.
Ataulf was stonewalled by Honorius in much the same fashion and saw that he'd have to switch strategies if his ends were to be met. He tried an alliance with Jovinus, usurper under Guntiarius, but these negotiations failed as well. So he moved his forces against the Jovinus-Sebastianus coalition, defeated them and re-installed Attalus as emperor. But by this time Honorius had recovered somewhat and was able to move against Ataulf under the leadership of Constantius III. Constantius blockaded Ataulf's supply route and, seeing that his position was untenable, retreated leaving Attalus to fend for himself. Attalus was captured in short order, mutilated and then exiled.
RIC 1414, LRBC 826 AE3 Obv: PRISCVSATTALVSPFAVG; Diademed, draped and cuirassed bust right.
Rev: VICTORIAROMANORVM; Victory advancing left and holding wreath.