Caesar's Civil War in the context of "Legio XIII Gemina"

Gaius Cassius Longinus (Classical Latin: [ˈɡaːi.ʊs ˈkassi.ʊs ˈlɔŋɡɪnʊs]; c. 86 BC – 3 October 42 BC) was a Roman senator and general best known as a leading instigator of the plot to assassinate Julius Caesar on 15 March 44 BC. He was the brother-in-law of Brutus, another leader of the conspiracy. He commanded troops with Brutus during the Battle of Philippi against the combined forces of Mark Antony and Octavian, Caesar's former supporters, and committed suicide after being defeated by Mark Antony.

Cassius was elected as tribune of the plebs in 49 BC. He opposed Caesar, and eventually he commanded a fleet against him during Caesar's Civil War: after Caesar defeated Pompey in the Battle of Pharsalus, Caesar overtook Cassius and forced him to surrender. After Caesar's death, Cassius fled to the east to Syria, where he amassed an army of twelve legions. He was supported and made governor by the Senate. Later he and Brutus marched west against the allies of the Second Triumvirate.

The Battle of Pharsalus was the decisive battle of Caesar's Civil War fought on 9 August 48 BC near Pharsalus in Central Greece. Julius Caesar and his allies formed up opposite the army of the Roman Republic under the command of Pompey. Pompey had the backing of a majority of Roman senators and his army significantly outnumbered the veteran Caesarian legions.

Pressured by his officers, Pompey reluctantly engaged in battle and suffered an overwhelming defeat, ultimately fleeing the camp and his men, disguised as an ordinary citizen. Eventually making his way to Egypt, he was assassinated upon his arrival at the order of Ptolemy XIII.

Marcus Junius Brutus (/ˈbruːtəs/; Latin: [ˈmaːrkʊs juːniʊs ˈbruːtʊs]; c. 85 BC – 23 October 42 BC) was a Roman politician, orator, and the most famous of the assassins of Julius Caesar. After being adopted by a relative, he used the name Quintus Servilius Caepio Brutus, which was retained as his legal name. He is often referred to simply as Brutus.

Early in his political career, Brutus opposed Pompey, who was responsible for Brutus' father's death. He also was close to Caesar. However, Caesar's attempts to evade accountability in the law courts put him at greater odds with his opponents in the Roman elite and the senate. Brutus eventually came to oppose Caesar and sided with Pompey against Caesar's forces during the ensuing civil war (49–45 BC). Pompey was defeated at the Battle of Pharsalus in 48, after which Brutus surrendered to Caesar, who granted him amnesty.

Publius Vatinius was a Roman politician during the last decades of the Republic. He served as a Caesarian-allied plebeian tribune in the year 59 – he was the tribune that proposed the law giving Caesar his Gallic command – and later fought on that side of the civil war. Caesar made him consul in 47 BC; he later fought in Illyricum for the Caesarians and celebrated a triumph for his victories there in 42 BC.

Titus Labienus (c. 100 BC – 17 March 45 BC) was a high-ranking military officer in the late Roman Republic. He served as tribune of the Plebs in 63 BC. Although mostly remembered as one of Julius Caesar's best lieutenants in Gaul and mentioned frequently in the accounts of his military campaigns, Labienus chose to oppose him during the Civil War and was killed at Munda. He was the father of Quintus Labienus.