Question: In what Wars did Gaius Cassius Longinus command troops?

Context paragraphs:
Alexander of Rhodes: Alexander (Ancient Greek: Ἀλέξανδρος ) was a prominent Rhodian who lived in the 1st century BC.  In the war against Gaius Cassius Longinus he was at the head of the popular party, and was raised to the office of prytanis, in 43 BC.  But soon after, he and the Rhodian admiral, Mnaseas, were defeated by Cassius in a naval battle off Knidos.

Lucius Cassius Longinus (proconsul): Lucius Cassius Longinus was the brother of the Gaius Cassius Longinus, a leading instigator in the assassination of Julius Caesar.

Serapion (strategos): Serapion ("presumed" died 41 BC) was strategos of Cyprus during the reign of Cleopatra VII in 43 BC.  Against the intention of the Egyptian queen he supported in the Roman civil war Gaius Cassius Longinus, but had to take refuge in Tyre and was finally handed over to Cleopatra in 41 BC.  Perhaps he is identical with that Serapion, who was instructed by Julius Caesar to negotiate in 48 BC with the Egyptian commander Achillas.

Philippi (Rome): "Philippi" is the sixth episode of the second season of the television series "Rome".  The episode portrays the civil war between the Second Triumvirate and the combined forces of Marcus Junius Brutus and Gaius Cassius Longinus, murderers of Julius Caesar.  The Battle of Philippi is featured in this episode.

Battle of Philippi: The Battle of Philippi was the final battle in the Wars of the Second Triumvirate between the forces of Mark Antony and Octavian (of the Second Triumvirate) and the leaders of Julius Caesar's assassination, Marcus Junius Brutus and Gaius Cassius Longinus in 42 BC, at Philippi in Macedonia.  The Second Triumvirate declared this civil war ostensibly to avenge Julius Caesar's assassination in 44 BC, but the underlying cause was a long-brewing class conflict between the "ancien regime" represented in the Senate (Optimates), and the rising class (Populares).

Gaius Cassius Longinus: Gaius Cassius Longinus (] ; October 3, before 85 BC – October 3, 42 BC) was a Roman senator, a leading instigator of the plot to kill Julius Caesar, and the brother in-law of Marcus Junius Brutus.  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.

Gaius Cassius Longinus (consul AD 30): Gaius Cassius Longinus was an Ancient Roman jurist and politician from the first century AD.  A grandnephew of Servius Sulpicius Rufus, he was also a descendant, great grandson or nephew, of Gaius Cassius Longinus, one of Caesar's assassins.

Carteia (gens): The gens Carteia was a Roman family towards the end of the Republic.  It is best remembered for a single individual, Lucius Carteius, a friend of Gaius Cassius Longinus, who was with Cassius in Syria in 43 B.C.

Gaius Cassius Longinus (Rome character): Gaius Cassius Longinus is a historical figure who features as a character in the HBO/BBC2 original television series "Rome", played by Guy Henry.  Cassius is depicted as a passion-filled man who is one of the first people who wants Caesar dead.  He is one of the figures who devised the plot for Caesar's death, and also acted as one of the assassins.  The real Cassius was also one of the main players in the death of Caesar.

Publius Licinius Crassus (consul 171 BC): Publius Licinius Crassus (fl.  171 BC) was Roman consul for year 171 BC, together with Gaius Cassius Longinus.

Supporting paragraphs: Gaius Cassius Longinus Battle of Philippi
Answer: Wars of the Second Triumvirate