sentences:  In frustration, Galerius allowed his legions to ravage the countryside as they passed northwards.Maxentius declined to make a general engagement.With so many emperors now in existence, in 308 Galerius, together with the retired emperor Diocletian and the now active Maximian, called an imperial 'conference' at Carnuntum on the River Danube to rectify the situation and bring some order back into the imperial government.