 On November 11 , 308 , to resolve the political instability , Galerius called Diocletian ( out of retirement ) and Maximian to a general council meeting at the military city of Carnuntum on the upper Danube . There , Maximian was forced to abdicate again and Constantine was again demoted to Caesar , with Maximinus the Caesar in the east . Licinius , a loyal military companion to Galerius , was appointed Augustus of the West In early 309 Maximian returned to the court of Constantine in Gaul , the only court that would still accept him . After Constantine and Maximinus refused to be placated with the titles of Sons of the Augusti , they were promoted in early 310 , with the result that there were now four Augusti . 
