Military tactics of the Roman Army are always interesting…and the tactical and political background of Pilate…
The Roman historian Tacitus calls Pilate a
procurator, and that’s what he was traditionally known as. But in 1961, a limestone block was discovered in the ruins of a theater at Caesarea Maritima (‘Caesarea-on-the-Sea’, the capital of Roman Judaea - no, it wasn’t Jerusalem

). The had a dedicatory inscription to the emperor Tiberius engraved in it, and it mentions Pilate by name - what’s interesting is that there, Pilate is given the title
praefectus, ‘prefect’.
http://www.english.imjnet.org.il/media/Uploads/Pontius-Pilate-Inscrip.jpg
So there’s a bit of a discrepancy. Which of the two titles are correct?
Most scholars think that the likely scenario was that the Roman governors of Judaea were known as ‘prefects’ from AD 6 (when the province of Judaea was formed out of the territories Herod Archelaus originally ruled over) up until AD 41. From AD 41 up to AD 44, Herod Agrippa was made ‘King of the Jews’ by the emperor Claudius (Herod the Great was technically the last ‘King of the Jews’; his sons like Antipas or Archelaus were really
not kings but tetrarchs, ‘rulers of a fourth’) and Judaea regained nominal autonomy. When Agrippa died, the province returned to Roman control, and governors once again ruled the area. Scholars think that it’s likely that the ‘procurator’ title was used from AD 44 onwards, and that Tacitus, who was writing in the late 1st century, simply gave the title (anachronistically) to Pilate.
I’m quoting from a paper by E.P. ‘Ed’ Sanders entitled
Jesus in Historical Context.
Judea in Jesus’ Day: What about Judea and, especially, its largest city, Jerusalem? It had a quite different fate [from that of Galilee] after Herod died. Here we encounter the other two ruling officials in Jesus’ day: the high priest Caiaphas and the Roman prefect Pilate. To explain how and why they governed Judea while Antipas governed Galilee, we have to go back to Herod’s death. When Herod died, Judea, Samaria, and Idumea were combined in a political unit called “Judea”; they were governed by another of Herod’s sons, Archelaus. He started out, as did Antipas, governing this region as his father had done before him. But things did not go well. Archelaus was probably less able than Antipas, and he certainly governed a more difficult region, since the Jews in Jerusalem were extremely touchy. But Archelaus seems also to have been clumsy. He did not know when to yield to the will of the populace and when to repress dissent. Both the Judeans and the Samaritans complained, and Augustus deposed him after ten years, in 6 CE. Augustus decided not to give this region to another of Herod’s sons, but to rule it directly, and he sent Coponius, a Roman of the equestrian order (thus, of some position in life), with a small number of troops, to govern Samaria, Judea, and Idumea. When this decision was made, there was a small uprising, but it was put down, and the Romans settled in to rule part of Palestine-
for the first time. They had conquered Palestine seventy years earlier, but had not governed any of it before, except for a very brief period after the initial conquest when they imposed military control before deciding on which Jews would rule the country.
How did these first Roman governors in Palestine conduct their administration? Coponius and his successors lived in one of Herod’s palaces in Herod’s most agreeable city, Caesarea on the Mediterranean, which was heavily gentile. There they had most of the amenities of home. There, too, were the Roman troops, about 3,000 of them, not enough to put down a serious uprising, but enough for minor riots limited to only one City. There were, we recall, more than 20,000 troops in Syria. In addition to the cohorts settled in Caesarea, there was a garrison in a fort next to the temple complex in Jerusalem, but its soldiers seldom had police duties. A few other very small garrisons were established in existing forts in other parts of the country. Those troops, too, had no regular police duties.
Jerusalem was a center of pilgrimage, and pilgrimage was a very popular activity in the ancient world. Three times a year, throngs of Jews from everywhere-Mesopotamia, North Africa, Asia Minor, Greece, and Italy-came to Jerusalem to celebrate one of the festivals, a kind of combination of state fair, silent worship, butchery of animals, eating red meat-a rare treat-and drinking wine. The population of Jerusalem suddenly swelled about tenfold (from 30,000 or so to over 300,000). Then and only then did the Roman prefect bring more troops to the city. On these occasions, they did assume some police duties, which were concentrated on the largest assembly point in Palestine, the courts of the temple. Soldiers patrolled the roofs of the colonnades that surrounded the enormous temple complex. Civil unrest was a well-known feature of large assemblies, and the Romans took due precautions. But 3,000 soldiers could not stop a serious effort by 300,000 to revolt. Real trouble required Roman troops from Syria.
During the forty-five or so weeks of each year that the Roman knight and his troops were not in Jerusalem, who policed the city and who was responsible for local government? The high priest, assisted by other aristocrats, many of whom were also priests. Police duties were the responsibility of the high priest’s guards. The high priest during Jesus’ adulthood was the very successful Joseph Caiphas, who held office for seventeen years, longer than any other high priest of the Roman period.