Ancient Rome had two major periods of history. The first was the Roman Republic which lasted from 509 BC to 27 BC. During this time there was no single leader of Rome. The government was run by elected officials. The second period was the Roman Empire which lasted from 27 BC to 476 AD (Western Roman Empire). During this time the government was led by an emperor.
During the time of the Roman Republic the top leaders of the Roman government were the consuls. There were two consuls at a time and they only served for one year. This kept any one man from becoming too powerful.
The fall of the Roman Republic began in 59 BC with an alliance between three powerful Roman politicians: Julius Caesar, Pompey the Great, and Marcus Licinius Crassus. This alliance became known as the First Triumvirate. These three men essentially ruled Rome. However, when Crassus died in battle in 53 BC, Pompey turned on Caesar and the two became enemies.
While Caesar was away from Rome leading his army, Pompey gathered political support against Caesar. Civil war erupted when Caesar led his army across the Rubicon River and approached Rome. Eventually Caesar defeated Pompey and became the most powerful man in Rome. Caesar's enemies did not want him to end the Roman Republic and become king, so they assassinated him in 44 BC.
After Caesar died, a Second Triumvirate formed between Mark Antony, Octavian (Caesar's heir), and Lepidus. The Second Triumvirate was officially recognized by the Roman government in 43 BC. Some historians consider this to be the end of the Roman Republic. The Second Triumvirate ruled for ten years until 33 BC. However, it began to split up when Octavian removed Lepidus from power in 36 BC.
Octavian Defeats Mark Antony
When the Second Triumvirate came to an end, a civil war began between Octavian and Mark Antony. While Mark Antony was with his army in the eastern portion of the empire, Octavian built a power base in Rome. He soon launched an attack against Mark Antony, who had allied with Cleopatra VII of Egypt. Octavian defeated Mark Antony and Cleopatra at the Battle of Actium in 31 BC.
The Roman Empire Begins
Octavian was now the most powerful man in all of Rome. In 27 BC, he had himself named "Augustus" and became the first Emperor of Rome. This marked the beginning of the Roman Empire. The first period of the Roman Empire was one of the most prosperous times of Ancient Rome. The empire expanded to cover its largest expanse and Rome became very wealthy.
Interesting Facts About Moving from the Roman Republic to the Roman Empire
Mark Antony married Octavia, Octavian's sister, but he had an affair with Cleopatra VII.
The Second Triumvirate was established by a law called the "Lex Titia." The three members were ranked above the level of the consuls.
Octavian was Caesar's heir, but wasn't his son. He was his great-nephew.
Mark Antony and Cleopatra both committed suicide when they realized they had lost the war.
The Roman Civil War began when Caesar's army crossed the Rubicon River. Today the saying "crossing the Rubicon" means you've passed the "point of no return."