Second Punic War (218-201 BC) – marked by Hannibal's surprising overland journey and his costly crossing of the Alps, followed by his reinforcement by Gaulish allies and crushing victories over Roman armies in the battle of the Trebia and the giant ambush at Trasimene.
Hannibal – Punic Carthaginian military commander, generally considered one of the greatest military commanders in history. Hannibal occupied much of Italy for 15 years, but a Roman counter-invasion of North Africa forced him to return to Carthage, where he was decisively defeated by Scipio Africanus at the Battle of Zama.
Battle of Zama – marked the final and decisive end of the Second Punic War. A Roman army led by Publius Cornelius Scipio Africanus defeated a Carthaginian force led by the legendary commander Hannibal. Soon after this defeat on their home ground, the Carthaginian senate sued for peace, which was given to them by the Roman Republic on rather humiliating terms, ending the 17-year war.
Third Punic War (149-146 BC) – involved an extended siege of Carthage, ending in the city's thorough destruction. The resurgence of the struggle can be explained by growing anti-Roman agitations in Hispania and Greece, and the visible improvement of Carthaginian wealth and martial power in the fifty years since the Second Punic War.
Crisis of the Roman Republic (134 BC-44 BC) – extended period of political instability and social unrest that culminated in the demise of the Roman Republic and the advent of the Roman Empire.
Principate (27 BC-284 AD) – first period of the Roman Empire, extending from the beginning of the reign of Caesar Augustus to the Crisis of the Third Century, after which it was replaced with the Dominate. During the Principate, the constitution of the Roman Republic was never formally abolished. It was amended in such a way as to maintain a politically correct façade of Republican government. This ended following the Crisis of the Third Century (235–284), during the reign of Diocletian.
Julio-Claudian dynasty (27 BC-68 AD) – the first five Roman Emperors, including Augustus, Tiberius, Caligula (also known as Gaius), Claudius, and Nero. The dynasty ended when Nero committed suicide.
Tiberius (ruled 14-37 AD) – stepson of Augustus. He was one of Rome's greatest generals, conquering Pannonia, Dalmatia, Raetia, and temporarily Germania; laying the foundations for the northern frontier. But he came to be remembered as a dark, reclusive, and sombre ruler who never really desired to be emperor; Pliny the Elder called him tristissimus hominum, "the gloomiest of men."[2]
Year of the Four Emperors (69 AD) – these four emperors were Galba, Otho, Vitellius, and Vespasian. Vespasian's rule marked the beginning of the Flavian dynasty.
Nerva–Antonine dynasty (96-192 AD) – dynasty of seven Roman Emperors who ruled over the Roman Empire from 96 AD to 192 AD. These Emperors were Nerva, Trajan, Hadrian, Antoninus Pius, Marcus Aurelius, Lucius Verus, and Commodus.
Crisis of the Third Century (235-284 AD) – period in which the Roman Empire nearly collapsed under the combined pressures of invasion, civil war, plague, and economic depression. The Crisis began with the assassination of Emperor Alexander Severus at the hands of his own troops, initiating a fifty-year period in which 20–25 claimants to the title of Emperor, mostly prominent Roman army generals, assumed imperial power over all or part of the Empire.
Barracks emperor – any Roman Emperor who seized power by virtue of his command of the army. Barracks emperors were especially common in the period from 235 through 284, during the Crisis of the Third Century.
Gallic Empire (260-274 AD) – modern name for a breakaway realm of the Roman Empire, founded by Postumus in 260 in the wake of barbarian invasions and instability in Rome, and at its height included the territories of Germania, Gaul, Britannia, and (briefly) Hispania.
Palmyrene Empire (260-273) – splinter empire, that broke away from the Roman Empire during the Crisis of the Third Century. It encompassed the Roman provinces of Syria Palaestina, Egypt and large parts of Asia Minor.
Dominate (284-476 AD) – 'despotic' latter phase of government in the ancient Roman Empire from the conclusion of the Third Century Crisis until the collapse of the Western Empire. The Emperor Diocletian abandoned the appearances of the Republic for the sake of control, and introduced a novel system of joint rule by four monarchs known as the Tetrarchy.
Decline of the Roman Empire – process spanning many centuries; there is no consensus when it might have begun but many dates and time lines have been proposed by historians.
Tetrarchy (293-313 AD) – Diocletian designated the general Maximian as co-emperor, first as Caesar (junior emperor) in 285, and then promoted him to Augustus in 286. Diocletian took care of matters in the Eastern regions of the Empire while Maximian similarly took charge of the Western regions. In 293, feeling more focus was needed on both civic and military problems, Diocletian, with Maximian's consent, expanded the imperial college by appointing two Caesars (one responsible to each Augustus). The tetrarchy collapsed, however, in 313 and a few years later Constantine I reunited the two administrative divisions of the Empire as sole Augustus.[3][4]
First Tetrarchy – created by Diocletian with Maximian's consent in 293 by the appointment of two subordinate Caesars.
Second Tetrarchy – in 305, the senior emperors jointly abdicated and retired, elevating Constantius and Galerius to the rank of Augusti. They in turn appointed two new Caesars.
Civil wars of the Tetrarchy – series of conflicts between the co-emperors of the Roman Empire, starting in 306 AD with the usurpation of Maxentius and the defeat of Severus, and ending with the defeat of Licinius at the hands of Constantine I in 324 AD.
Constantinian dynasty – informal name for the ruling family of the Roman Empire from Constantius Chlorus (†305) to the death of Julian in 363. It is named after its most famous member, Constantine the Great who became the sole ruler of the empire in 324. It is also called the Neo-Flavian dynasty.
Division of the Roman Empire – in order to maintain control and improve administration, various schemes to divide the work of the Roman Emperor by sharing it between individuals were tried between 285 and 324, from 337 to 350, from 364 to 392, and again between 395 and 480. Although the administrative subdivisions varied, they generally involved a division of labour between East and West. Each division was a form of power-sharing (or even job-sharing), for the ultimate imperium was not divisible and therefore the empire remained legally one state—although the co-emperors often saw each other as rivals or enemies rather than partners.
Western Roman Empire – In 285, Emperor Diocletian (r. 284–305) divided the Roman Empire's administration into western and eastern halves.[5] In 293, Rome lost its capital status, and Milan became the capital.
Byzantine Empire (Eastern Roman Empire) – term used by modern historians to distinguish the Constantinople-centered Roman Empire of the Middle Ages from its earlier classical existence.
Nicomedia – Nicomedia was the metropolis of Bithynia under the Roman Empire, and Diocletian made it the eastern capital city of the Roman Empire in 286 when he introduced the Tetrarchy system.
Constantinople – founded in AD 330, at ancient Byzantium as the new capital of the entire Roman Empire by Constantine the Great, after whom it was named.
Fall of the Western Roman Empire (476 AD) – the two halves of the Roman Empire ended at different times, with the Western Roman Empire coming to an end in 476 AD (the end of Ancient Rome). The Eastern Roman Empire (referred to by historians as the Byzantine Empire) survived for nearly a thousand years more, and eventually engulfed much of the Western Roman Empire's former territory.
Fall of the Western Roman Empire – this was not sudden, and took over a hundred years. By 476, when Odoacer deposed the Emperor Romulus, the Western Roman Empire wielded negligible military, political, or financial power and had no effective control over the scattered Western domains that still described themselves as Roman.
Odoacer – Germanic soldier, who in 476 became the first King of Italy (476-493). His reign is commonly seen as marking the end of the Western Roman Empire.[6]
Byzantine Empire (Byzantium) – after the Western Roman Empire fragmented and collapsed, the Eastern Roman Empire (Byzantium) continued to thrive, existing for nearly another thousand years until it fell to the Ottoman Turks in 1453. Its citizens referred to it as the Roman Empire, and saw it as a direct continuation of it. Historians consider it to be a distinctly different empire, with some overlap, but generally not included in the period referred to as Ancient Rome. Byzantium differed in major ways, including its primary language, which was Greek rather than Latin. It also differed religiously, with Roman mythology being replaced by Christianity.
Legacy of the Roman Empire – what the Roman Empire passed on, in the form of cultural values, religious beliefs, as well as technological and other achievements, and through which it continued to shape other civilizations, a process which continues to this day.
^Bury, John Bagnall (1923). History of the Later Roman Empire. Macmillan. p. 1.
^Kuhoff, Wolfgang (2002). "Die diokletianische Tetrarchie als Epoche einer historischen Wende in antiker und moderner Sicht". International Journal of the Classical Tradition. 9 (2): 177–178. doi:10.1007/BF02898434. JSTOR30224306.
^"Odoacer was the first barbarian who reigned over Italy, over a people who had once asserted their just superiority above the rest of mankind." Edward Gibbon, The Decline and Fall of the Roman Empire, Chapter XXXVI