Wikipedia
Established in December 1917, Dunsterforce was an Allied military force named after its commander, General Lionel Dunsterville. The force had fewer than New Zealand, British and Canadian officers and NCOs, drawn from the Western and Mesopotamian fronts. The force was intended to organise local units in northern Iran and southern Caucasus, to replace the Tsarist armies that had fought the Ottoman armies in Armenia. The Russians had also occupied northern Iran in co-operation with the British occupation of south Iran, to create a cordon to prevent German and Ottoman agents from reaching central Asia, Afghanistan and India.
The British and Russian empires had informally partitioned Iran in the Anglo-Russian Convention of 1907 and sent occupation forces into the country on the outbreak of war in 1914. The occupation was intended to counter possible Ottoman and German intrigues to destabilise Iran, Afghanistan, India and Central Asia. (In 1935, Reza Shah asked that the international community to refer to the country by its native name, Iran. Opposition to the change led to the reversal of the decision and Professor Ehsan Yarshater, editor of Encyclopædia Iranica, proposed the use of Persia and Iran interchangeably.)
In July 1918, Captain Stanley Savige, five officers and fifteen NCOs of Dunsterforce set out towards Urmia and found themselves swept up in the exodus of Assyrians, after the town was captured by the Ottoman army. About had fled and were defended by the Dunsterforce party, that helped hold off the Ottoman pursuit and the attempts by local Kurds to get revenge on the Assyrians, for their earlier plundering. By the time the rearguard reached Bijar on 17 August, the Dunsterforce party was so worn out, that only four recovered before the war ended. A combined infantry and cavalry brigade was raised from the Assyrian survivors to re-capture of Urmia and the rest of the civilians were sent to refugee camps Baqubah near Baghdad.
Dunsterville and the rest of the force, with reinforcements from the 39th Infantry Brigade, drove in and armoured cars, about from Hamadan across Qajar Iran to Baku. Dunsterforce fought in the Battle of Baku from The force retreated from the city on the night of and two days later, Dunsterforce was disbanded. North Persia Force (Norper Force, Major-General W. M. Thomson) then took over the command of the troops in northern Iran. Troops diverted from Dunsterforce in Sweet's Column opposed an Ottoman diversion from Tabriz on the Persian road during September and on 19 September, the situation was transformed by the great British victory in Palestine, at the Battle of Megiddo The army in Caucasus was the only source of Ottoman reinforcements and had to give up divisions and end offensive operations in the theatre.