History of the Roman Empire founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically inclined Marcus Aurelius. In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD marked the descent "from a kingdom of gold to one of rust and iron"—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire. In 212, during the reign of Caracalla, Roman citizenship was granted
History of the Roman Empire who, eager to have all of the glory for himself, rushed into battle. On August 9, 378, the Battle of Adrianople resulted in the crushing defeat of the Romans and the death of Valens. Contemporary historian Ammianus Marcellinus estimated that two-thirds of the Roman army were lost in the battle. The battle had far-reaching consequences. Veteran soldiers and valuable administrators were among the heavy casualties. There were few available replacements at the time, leaving the Empire with the problem of finding suitable leadership. The Roman army also started to face recruiting problems. In the following century much of the Roman