David Hambling cites The Times History Of The War, published in the 1920s, which explains How To Pacify Iraq, 1918 Style:
“It was one of Sir Percy Cox’s first triumphs that he brought about a friendly understanding between the Shi’ites and Sunnites at Baghdad… The jurisdiction of the religious heads of the various communities was recognised and strengthened. The Baghdadi of all sects responded by giving willing help to the British authorities.”The capital gained a new police force and a fire brigade, numerous schools, electric street lighting and a reliable water supply. Mosques were repaired, roads built, and “sanitary squads have penetrated the most hidden purlieus pf the city.”
Under the new system of law, justice was executed “but people found that account was taken of their customs, and even the prejudices, and that no attempt was made to thrust upon them a British and alien system.”
Meanwhile, thousands of workers were taken on at Basra to develop the port, and the railway was extended from Basra to Baghdad. (The British Empire loved railways, which were essential for the rapid movement as troops — as well as for opening up new markets and new sources of supply.)
One problem was the perpetual feuding between tribes, which had apparently been encouraged by the Turks. All boundary disputes were settled on the basis of tribal custom and the authority of the local sheikhs. This was made possible by “the personal friendship and confidence which exists between them [the British political officers] and many of the sheikhs with whom they have had to deal. “ Interestingly, it notes that “in two cases at least it was noted that the head of the tribe was a woman.”
All in all, it seems a lot more politically correct than one might have expected ninety years ago.
Of course, one reason this all worked was that the British didn’t mess around:
One serious incident did occur at the holy city of Najaf, which was inhabited largely by “well-disposed holy people” but also a hard core of “irreconcilables” who would not accept the British. Some of the latter fired on British troops “causing a few casualties.” Captain W. M. Marshall, the political officer decided against violent punitive action, “not wishing to injure a town which is full of sacred memories for Mahommedans” and instead ordered the arrest of the two Sheikhs known to be responsible. They fled before they could be captured, and were presumably replaced by rulers who were more cautious about openly attacking the British.When a British officer was later killed at Najaf, a blockade was ordered. The town was surrounded by military posts connected with barbed wire until those implicated in the murder were given up.
The marshes of lower Mesopotamia were seen as a particular challenge, being full of outlaws and feuding tribes. But within twelve months they were pacified with “security of tenure, just taxation, water for their lands, safe transport and an assured market for their produce.”
A unit was formed from the former outlaws to police the area, providing “an outlet for restless spirits and opportunity of honorable employment to petty chiefs and impoverished members of ruling families.”