86. Beginning of the wars between the Romans and the Dacians.
98-117. Trajan, emperor of Rome. Under him the empire acquires its greatest territorial extent by his conquests in Dacia and in the East. His successor, Hadrian, abandons the provinces beyond the Euphrates, which Trajan had conquered.
138-180. Era of the Antonines.
167-176. A long and desperate war between Rome and a great confederacy of the German nations. Marcus Antoninus at last succeeds in repelling them.
192-197. Civil Wars throughout the Roman world. Severus becomes emperor. He relaxes the discipline of the soldiers. After his death in 211, the series of military insurrections, civil wars, and murders of emperors recommences.
226. Artaxerxes (Ardisheer) overthrows the Parthian, and restores the Persian kingdom in Asia. He attacks the Roman possessions in the East.
260. The Goths invade the Roman provinces. The emperor Decius is defeated and slain by them.
253-260. The Franks and Alemanni invade Gaul, Spain, and Africa. The Goths attack Asia Minor and Greece. The Persians conquer Armenia. Their king, Sapor, defeats the Roman emperor Valerian, and takes him prisoner. General distress of the Roman empire.
268-283. The emperors Claudius, Aurelian, Tacitus, Probus, and Carus defeat the various enemies of Rome, and restore order in the Roman state.
285. Diocletian divides and reorganizes the Roman empire. After his abdication in 305 a fresh series of civil wars and confusion ensues. Constantine, the first Christian emperor, reunites the empire in 324.