Vercingetorix, chieftain of the Arverni, was a prominent Gallic chieftain during the Gallic wars. Seeing that the divisions among Gallic tribes were being exploited by Caesar, he eventually became the king of a confederation of tribes, and even managing to defeat the Romans at Gergovia. However, he was defeated and captured during the Battle of Alesia, after which Caesar shipped him back to Rome to act as a trophy for the victorious Romans. After Caesar felt he had outlived his usefulness, he had him strangled in his prison cell. 

Spartacus was a Thracian slave who, after beginning the Third Servile War, revealed himself to be a surprisingly able general in the field. He was able to move up and down the Italian countryside with impunity before being defeated by a Roman army under Crassus. In the modern era, Spartacus has come to envision the plight of the common man, most notably in the Stanley Kubrick film that bears his name. 

Crassus, blinded by the riches of the Parthian Empire, led an army into Parthian territory with the intent of conquering Parthia and claiming its riches for himself. Crassus also wanted to prove himself as a capable military leader after being upstaged by Pompey during the Third Servile War. However, he made a number of blunders (outpacing his supply lines, going to far into Parthia without support, etc.) When the Parthians did attack, the Romans were exhausted and starved, leading to one of the most resounding defeats in the entire history of Rome. 

The Battle of Actium, off the coast of Greece, finally decided the war between Octavian (later Augustus) and Marc Antony. With his naval power crushed, Antony could no longer mount a campaign against Octavian, who already held Italy. This led to his infamous joint suicide with Cleopatra. Octavian became sole emperor of Rome, as well as the first true emperor of Rome. 

While Actium made Octavian Emperor of Rome, it was Agrippa who led the actual fighting. Octavian's friend from childhood, Agrippa was a fearsome naval strategist and powerful ally, so much so as to marry Julia, the emperor's only daughter. Later in life, he would fall out of favor with Augustus, only to be recalled when needed to quell rumblings of uprising in Rome. 

The Gallic Wars, and the journal of the same name, refer to the series of conflicts with Gallic tribes that eventually brought Gaul (modern-day France) into the Roman fold. While his tactics were brilliant, Caesar's motives were more suspect, as he used wealth gathered from Gaul during his campaigns to fund his eventual bid for Emperor in Rome. Be that as it may, Commentaries on the Gallic Wars is still studied in military history classes today.

The Persian empire was the preeminent power in what is now the Middle East for much of antiquity. After securing power in what is now Turkey, including a number of Ionian Greek cities on the coast, Greece became a natural place to expand. However, both expeditions ended in failure, and Persia was never able conquer the peninsula. 

The phalanx was a rectangular mass of troops, normally with spears, pikes or other long melee weapons. They were almost impossible to attack head on, as troops would rush right into a mass of spears. The phalanx would meet its match in the more flexible Roman legion, falling out of style as the Romans ascended. 

Hannibal Barca, one of the preeminent military minds of his age, nearly managed to destroy the Roman Empire. Using a daring traversal of the Alps with his War Elephants, Hannibal reached the gates of Rome before lack of supply and reinforcement made him retreat. After the fall of Carthage, he fled to modern-day Turkey, a guest of monarchs and a living symbol of Roman vulnerability. 

The Revolt of the Ionian Greek cities (in modern day Turkey) was the perfect excuse for Darius to invade the Greek mainland. As cities such as Athens aided the rebel cities, Darius was able to construe this as an act of war and wage his campaign to expand his empire. Unfortunately for Darius, he did not count on the Greeks' resolve and knowledge of their own terrain, which resulted in his defeat at the Battle of Marathon.