The dogs of war are howling once more in Mesopotamia. It almost defies belief that voices are once more being raised, suggesting that “something must be done” to stop the dreaded Islamist bogeymen from taking Baghdad.

It’s worth remembering the first imperial invasion of the region – a grubby and vicious assault motivated by the need for oil.

One hundred years ago, British troops (actually, most of the troops were Indian, but they were under British command) occupied the port of Basra. Basra wasn’t then part of Iraq for the simple reason that there was no such country. It was part of the Ottoman province of Mesopotamia.

The timing of the operation bears close inspection. The occupation took place on 21 November 1914. The first hostile act, however, was the penetration of the Shatt-al-Arab (the river formed by the joining of the Euphrates and the Tigris, which flows into the Persian Gulf at the border of Iraq and Iran), by two British warships, HMS Espiegle and Dalhousie on 29 September.

The Turks declared war on 28 October, and the Allies declared war on them on 4 November. You can read in the standard history books various discussions of why the Turks joined the war on Germany’s side. In none of them have I found any mention of the fact that the British were clearly preparing an invasion and had begun hostile activity a month before war was declared.

A key to the British motivation can be found in an agreement signed between the British and the Ottomans in 1913 regarding the status of Kuwait, which had been a de facto British protectorate since 1899. The British acknowledged that Kuwait was a part (albeit a “self-governing” part) of the Ottoman Empire, but they did so in the knowledge that they in fact were in control and that the sheikh of Kuwait had signed an agreement giving the British the rights to any oil that might be discovered there.

Oil was not discovered until the 1930s. But it was understood that such a discovery was a possibility. Oil had been discovered in Persia in 1908 and was being extracted by Anglo-Persian Oil, one of the ancestors of BP. Oil exploration in neighbouring Mesopotamia soon struck black gold at Mosul, and the “Turkish Petroleum Company” was founded in 1911 to exploit it. The company was Turkish only in name. The capital involved was mainly British and Dutch with, curiously, some German minority interests.

Oil had suddenly become a very important commodity. In 1911 Winston Churchill, the new first lord of the Admiralty, finally won a battle to get the British navy to begin changing from coal-powered to oil-powered vessels. Using oil would make the ships lighter and faster and would enable them to be refuelled at sea.

Admiral Fisher had previously been unable to win the Admiralty to such a change. Ruling class conservatism, bolstered by a belief that there wasn’t enough oil in the world to supply the fleet, had held him off, but the discovery of oil in the Middle East turned the tide in this bureaucratic war. It also sealed the fate of the Ottoman Empire.

Basra was secured with little difficulty, but the subsequent march on Baghdad was a military disaster. The British were defeated at Ctesiphon in November 1915 and forced to retreat to Kut-al-Amara, where one of the Indian divisions was surrounded. There followed a five-month siege and a number of unsuccessful attempts to relieve the garrison, which surrendered to the Turks in April 1916.

It was a disaster for the British, but successes in Palestine would eventually allow them to advance again, and they occupied Baghdad in March 1917. The first thing the British did upon the Ottoman surrender in October 1918 was rush troops to secure Mosul and the oilfields. By 1920, with the new “Kingdom of Iraq” having been established with a British puppet on the throne, RAF planes were bombing rebellious Kurdish villages. This happened, of course, 17 years before Guernica.

A war for oil – it’s a good thing we don’t have them any more.