Constantius responded by dispatching to Cologne a flying-squad of "protectores domestici" (imperial staff-officers), including the future historian Ammianus himself, under the command of Ursicinus. These soon contrived to murder Silvanus and prevented a wider mutiny. But the shaken emperor decided that he needed a member of his own imperial dynasty (the House of Constantine, known to the Romans as the "Flavii", after Constantine the Great's clan name) to share the burdens of governing the empire. This was a difficult decision for a paranoid ruler who regarded all his relatives with intense suspicion and had already put to death 2 of his uncles and 7 cousins, including Julian's half-brother Constantius Gallus. (Although the House of Constantine was the first Roman imperial dynasty to profess the Christian faith, its internal strife was as ruthless as any of its predecessors). He appointed his cousin Julian as "Caesar" (deputy emperor) for the "Three Gauls" (the dioceses of Gaul, Spain, and Britain) and gave him overall command of forces in Gaul. The appointment, though greeted with enthusiasm by the troops at Milan, was more generally seen as unsuitable as Julian, who was just 23 years old, had no military experience and until that moment had spent his time studying philosophy at Athens. But Constantius' own family purges had left him little choice: Julian was his sole surviving adult male close relative. The task confronting Julian as he took up his command was daunting. The civil war had left Gaul in a chaotic state. The defensive line of the Rhine had largely collapsed. According to Ammianus, "Mogontiacum" (Mainz), "Borbetomagus" (Worms), "Nemetae Vangionum" (Speyer), "Tabernae" (Saverne), "Saliso" (Brumat), and "Argentorate" (Strasbourg) were all in German hands. Apart from the major fortified city of "Colonia Agrippina" (Cologne), only three strongpoints on the Rhine remained in Roman hands: a single tower near Cologne and two forts, at "Rigodunum" (Remagen) and "Confluentes" (Koblenz). Large barbarian bands were roaming and pillaging northeastern Gaul at will, reaching as far as the River Seine. So many and so large were the marauding enemy bands that Silvanus was considered a brave man for having led a large force (8,000 men) along a wooded highway in the heart of Gaul because of the risk of ambush.