A brief orientation
Marcus Porcius Cato the Younger — Cato Uticensis, after the place of his death — was a Roman senator, magistrate and self-described follower of the Stoic philosophy. His career ran in parallel with Caesar's. He was tribune in 62 BCE, served as a praetor and was elected (and rejected) for the consulship; he was one of the senate's most consistent opponents of the First Triumvirate and one of the most consistent voices for prosecuting Caesar after the Gallic command. When the civil war began he joined the senatorial side under Pompey; after Pompey's defeat at Pharsalus and death in Egypt, Cato made his way to the African remnant of the senatorial forces. After the senatorial defeat at Thapsus in 46 he refused either to flee further or to accept Caesar's clemency and committed suicide at Utica, reading Plato's Phaedo as he did.
The reception
Cicero, who disagreed with Cato on details of political tactics for nearly all of their adult lives, wrote a Cato after his death praising him; Caesar wrote a furious Anticato in reply (neither survives). The example became one of the most sustained sources of the European republican tradition's idea of civic virtue. Seneca returned to him repeatedly; Plutarch wrote his Life; the early-modern reception ran from Petrarch through Joseph Addison's Cato (1713) — the play George Washington had performed for his army at Valley Forge — through to the American founders' explicit invocations of him.
The argument over his judgement
The ancient tradition was not unanimous in admiring Cato. Sallust acknowledged the virtue; Caesar's circle treated him as obstinate in ways that helped collapse the senatorial cause; Cicero in private letters wished he would compromise more. The modern reading generally splits along the same lines: Cato as the man whose unbending integrity preserved the moral case against Caesar even at the cost of practical defeat, or Cato as the man whose unbending integrity made the practical defeat inevitable.
Why he matters for Virtue & Power
Cato is the platform's case for civic virtue at full intensity — at the cost of life, with no consolation that the cause will win in his lifetime, without the option of a compromise that would have made the cost lower. The classical and modern republican traditions made him into a type because the type is hard to live and hard to refuse.