480 – Odoacer, first King of Italy, occupies Dalmatia

9 December

Flavius Odoacer (433–493), was a 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.

 Though the real power in Italy was in his hands, he represented himself as the client of Julius Nepos and, after Nepos' death in 480, of the Emperor in Constantinople. Odoacer generally used the Roman honorific patrician, granted by the Emperor Zeno, but is referred to as a king (Latin rex) in many documents and he himself used it at least once and on another occasion it was used by the consul Basilius. Odoacer introduced few important changes into the administrative system of Italy. He had the support of the Roman Senate and was able to distribute land to his followers without much opposition. Unrest among his warriors led to violence in 477–478, but no such disturbances occurred during the later period of his reign. Although Odoacer was an Arian Christian, he rarely intervened in the affairs of the orthodox and trinitarian state church of the Roman Empire.

Probably of Scirian descent, Odoacer was a military leader in Italy who led the revolt of Herulian, Rugian, and Scirian soldiers that deposed Romulus Augustulus on 4 September AD 476. Augustulus had been declared Western Roman Emperor by his father, the rebellious general of the army in Italy, less than a year before, but had been unable to gain allegiance or recognition beyond central Italy. With the backing of the Roman Senate, Odoacer thenceforth ruled Italy autonomously, paying lip service to the authority of Julius Nepos, the last Western emperor and Zeno the emperor of the East. Upon Nepos' murder in 480 Odoacer invaded Dalmatia, to punish the murderers. He did so, executing the conspirators, but within two years also conquered the region and incorporated it into his domain. 

Odoacer is the earliest ruler of Italy for whom an autograph of any of his legal acts has survived to the current day. The larger portion of a record of Odoacer granting properties in Sicily and the island of Melita on the Adriatic coast to Pierius and issued in 488, was written in his reign.

602 – Emperor Maurice is executed

27 November

Maurice Flavius Mauricius Tiberius Augustus 539 – 27 Nov 602 was Byzantine Emperor from 582 to 602. Maurice was murdered on this day in 602. It is said that the deposed emperor was forced to watch his six sons executed before he was beheaded himself. Empress Constantina and her three daughters were spared and sent to a monastery.

A prominent general in his youth, Maurice fought with success against the Sassanid Persians. Once he became Emperor, he brought the war with Persia to a victorious conclusion and the Empire's eastern border in the Caucasus was vastly expanded and for the first time in nearly two centuries the Byzantines were no longer obliged to pay the Persians thousands of pounds of gold annually for peace.

Maurice campaigned extensively in the Balkans against the Avars – pushing them back across the Danube by 599. He also conducted campaigns across the Danube, the first Emperor to do so in over two hundred years. In the West, he established two large semi-autonomous provinces called exarchates, ruled by exarchs, or viceroys, of the emperor. In Italy, Maurice established the Exarchate of Ravenna in 584, the first real effort by the Empire to halt the advance of the Lombards. With the creation of the Exarchate of Africa in 590, he further solidified the empire's hold on the western Mediterranean.

His reign was troubled by financial difficulties and almost constant warfare. In 602, a dissatisfied general named Phocas usurped the throne, having Maurice and his six sons executed. This event would prove cataclysmic for the Empire, sparking a devastating war with Persia that would leave both empires weakened prior to the Muslim invasions.

His reign is a relatively accurately documented era of Late Antiquity, in particular by the historian Theophylact Simocatta.

284 – Diocletian is chosen as Roman emperor

Diocletian (245–311) was a Roman emperor from 284 to 305. Born to a family of low status in the Roman province of Dalmatia, Diocletian rose through the ranks of the military to become cavalry commander to the Emperor Carus.

After the deaths of Carus and his son Numerian on campaign in Persia, Diocletian was proclaimed emperor. The title was also claimed by Carus' other surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus. Diocletian's reign stabilized the empire and marks the end of the Crisis of the Third Century. He appointed fellow officer Maximian as Augustus, co-emperor, in 286.