Valerian the Elder and Gallienus (1 agos 253 año – 1 ene 268 año)
Descripción:
 Valerian was proclaimed Emperor by both Raetian soldiers and Aeumilanius' legion.  He joint-ruled with his son. Valerian was captured as a POW by the Persian Emperor, Shapur I. Gallienus becomes sole Emperor. Gallienus defeated the usurper Ingenuus in 258 and destroyed an Alemanni army at Mediolanum in 259, which is a main reason as to why he had such a long reign (15 years). 
Añadido al timeline:
fecha:
1 agos 253 año
1 ene 268 año
 ~ 14 years