A brief orientation
Gnaeus Pompeius Magnus was a Roman general of equestrian family whose career was characterised, from his early twenties, by extraordinary commands well outside the cursus honorum. He fought under Sulla, was awarded the cognomen Magnus before he had held a regular magistracy, swept piracy from the Mediterranean under the lex Gabinia (67 BCE), took on the long Mithridatic War and finished it (66–63 BCE), and returned from the East a richer and more famous man than Rome had previously seen. The settlement of the eastern provinces he negotiated formed a substantial part of Roman imperial administration for the next century.
The political weight
Pompey's standing was so unusual that even his ordinary requests — land for his veterans, ratification of his Eastern arrangements — could not be obtained through normal senatorial channels. The First Triumvirate of 60–53 BCE — the informal political alliance of Pompey, Caesar and Crassus — was the response: a private arrangement among three men whose combined weight could move what the senate would not. The Triumvirate was not a constitutional body; its effective operation was itself one of the most explicit signs of Republican institutional failure.
The civil war
After the death of Crassus at Carrhae in 53 and the breakdown of the working relationship with Caesar, Pompey returned to the senatorial faction and accepted the consulship sine collega — sole consul, a position normally restricted to dictators — to manage the political crisis. When Caesar refused to lay down his command and crossed the Rubicon in early 49, the open civil war began. Pompey led the senatorial forces, abandoned Italy for the East where his old networks were, was defeated at Pharsalus in 48 BCE, and was murdered shortly afterwards on landing in Egypt.
Why he matters for Virtue & Power
Pompey is the figure on whom the late Republic's most genuinely ambivalent reading sits. His career was, throughout, a sequence of extraordinary departures from constitutional norm — but he aligned himself, in the end, with the senate against Caesar's larger departure. Whether he was the defender of a still-living Republic or the man whose own career had hollowed it out so that the defence could not hold is the question the long literature has been turning over since Plutarch. See the essay Pompey versus Caesar.