Roman governor of Syria who not only failed to quell the Jewish uprising in 66 CE but whose humiliating defeat fanned the rebels' resistance to Roman forces. Gaius Cestius Gallus was a former consul of Rome (42 CE) whom Nero put in control of greater Syria, including Palestine (63 CE). So when the prefect of Judea (Gessius Florus) had to withdraw his troops for inciting rioting, Gallus intervened with the 12th Legion. But as a commander with no known prior experience in battle he made many tactical errors. Leaving contingents to occupy Galilee & the coast, he marched on Jerusalem with his supplies vulnerable to raids at the rear of his column. Then, after an unsuccessful nine day siege of Jerusalem he decided to retreat to the coast for no apparent reason. Failing to command the higher ground, his depleted legion was ambushed by Jews in the pass below Beth Horon. With most of his troops killed or wounded, Gallus barely managed to escape to Antioch.

 News of this victory over Roman forces inspired more Jews to join the uprising. So instead of restoring order by pacifying a subject population, Gallus created the conditions for a war that lasted another seven years. Shamed & disheartened by his ignominious defeat, Gallus died the following year. 

References: Josephus, War pref.; 2.14-20.
                  Tacitus, Histories 5.10.

Other resources on line:

• Gallus, Caius Cestius - article by Richard Gottheil & Samuel Krauss in 1906 Jewish Encyclopedia.

• The Campaign of Cestius Gallus and Defeat of the Twelfth Legion - G. J. Goldberg's illustrated analysis & chronology of the campaign [Josephus.org].

• Cestius Gallus - article in Wikipedia's web.