with so many emperors now in existence, in 308 galerius, the retired emperor diocletian and maximian called an imperial 'conference' at carnuntum on the river danube. its aim was to bring some order back into the imperial government. here it was agreed that galerius’ long-time friend and military companion licinius, who had been entrusted by galerius with the defense of the danube while galerius was in italy, would become augustus in the west, with constantine as his caesar. in the east, galerius remained augustus and maximinus remained his caesar. maximian was to retire, and maxentius was declared a usurper.