Short answers, pulled from the story.
Publius Licinius Egnatius Gallienus entered the world around 218 AD in Falerii, an ancient city located in Etruria. His exact birth date remains lost to history despite inscriptions connecting him to the Egnatii family.
Gallienus had three sons named Valerian II, Saloninus, and Marinianus who all died violently during his reign. Valerian II likely died on the Danube in 258, Saloninus was executed in 260 by General Postumus's army, and Marinianus was killed shortly after 268 by order of the new regime.
Gallienus commissioned primarily cavalry units known as Comitatenses that could be dispatched quickly across the empire. He also forbade senators from becoming military commanders which allowed equestrian commanders to rise to prominence and laid groundwork for future emperors like Diocletian and Constantine I.
Publius Licinius Egnatius Gallienus was murdered in 268 while besieging Milan against the usurper Aureolus. He left his tent without a bodyguard after Cecropius spread false news about Aureolus's forces leaving and was struck down by Cecropius.
The tomb of Publius Licinius Egnatius Gallienus is believed to be located south of Rome at the IXth mile of the Via Appia. This site marks the final resting place of the emperor who died during a campaign against Aureolus.