The Qajar government's inability to maintain the country's sovereignty during and immediately after the First World War led to a coup d'état in 1921 and Reza Shah's establishment of the Pahlavi dynasty.

[citation needed] The German Empire established their Intelligence Bureau for the East on the eve of World War I, dedicated to promoting and sustaining subversive and nationalist agitations in British India and the Persian and Egyptian satellite states.

The Ottoman Minister of War, Enver Pasha, claimed that if the Russians could be beaten in the key cities of Persia, it could open the way to Azerbaijan, to Central Asia and to India.

Although nationalist movements throughout the region led to political upheaval in nearly all European colonies in Asia during World War I and the interwar period, decolonisation on the scale of Enver's ambitions was never achieved.

[14] The Anglo-Persian Oil Company was in the proposed path of Enver's project: the British had the exclusive rights to work petroleum deposits throughout the Persian Empire except in the northern provinces of Azerbaijan, Gilan, Mazendaran, Astarabad and Khorasan.

In 1914, the British Indian Army had several units located in the southern influence zone; its officers were experienced in fighting tribal forces through decades of conflict on the North-Western Frontier.

The Persian Cossack Brigade and a small contingent of the Russian Caucasus Army under the Armenian General Tovmas Nazarbekian was stationed there.

The Cossack Brigade consisted of eight squadrons, a small battalion of infantry and a horse battery of six Krupp guns; their total strength did not exceed 2,000.

Besides this force, in 1912 Russia obtained the formal consent of the Persian government to the formation of a similar Cossack Brigade at Tabriz under Russian officers.

This measure enabled the Russians not only to control Persia, but also to secure the road from their rail-head at Djoulfa to the Van Province of the Ottoman Empire through Khoi.

[17] On 4 January 1915, a volunteer detachment led by Omer Naci Bey, who was sent to Persia on a special mission by Talat Pasha, captured the city of Urmia.

One week later, the "Mosul Group" commanded by Omer Fevzi Bey entered Tabriz without facing much resistance, having apparently taken the Russian leadership completely by surprise.

Though referred as Khalil Bey by Aram, Omer Fevzi with his (superior) forces captured the city of Urmia in a few hours and marched on Salmast.

The objective was the city of Dilman, and to clean this region from Nazarbekov's forces, which would provide a significant tactical advantage in the Caucasian Campaign.

[18] General Nazarbekov managed to push Halil Pasha regulars towards Başkale after the Battle of Diliman (15 April 1915), securing the situation.

In November 1915, Colonel Pessian, the commander of the Gendarmerie in Hamedan, launched an attack on the pro-Russian Persian Cossack Brigade at the Battle of Musalla.

During the last days of 1915, Sir Percy Sykes, with the temporary rank of Brigadier-General, was tasked with establishing a force of South Persia Rifles, to be drawn from the local tribesmen by means of financial inducements.

In fact, a Cossack company of five officers and 110 men left Baratov's Russian division on 8 May, rode southward for about 180 miles through the territory of disaffected tribesmen, crossed several mountain passes at altitudes of up to 8,000 feet, and reached the British front on the Tigris on 18 May.

For his part, Baratov hoped to capture Khanaqin and advance to Baghdad, sensing an opportunity to take the city as the British and Ottomans exhausted one another.

The squads within the expedition were led by the Church of the East Patriarch's brother Dawid; Ismail, Malka of the Upper Tyari; and Andreus, the Jilu Malik.

In January 1917, the Grand Duke Dimitri Pavlovich Romanov was sent to join Baratov, and they established a Cavalry Corps headquarters at Qazvin, in northern Persia.

The new government removed the Grand Duke from his command and reassigned General Yudenich to a meaningless position in Central Asia, prompting his resignation.

The Russian collapse left Van completely cut off from the Allies, and the British Army in Mesopotamia seemed unwilling to move very far beyond Baghdad.

[21] The military goal of this "Dunsterforce" was to reach the Caucasus via Persia, and, once there, to recruit and organize an army from the Armenians and other pro-Ally elements in the Caucuses.

[citation needed] In April 1918, the Armenians of Van province were eventually evacuated and withdrawn from the region and retreated eastward toward Iranian Azerbaijan.

[citation needed] During July 1918, the British Army captured the greater portion of Mesopotamia during the Mesopotamian Campaign, as well as a large parts of Iranian Azerbaijan.

[citation needed] In 1918, about half of the Assyrians of Persia died of Turkish and Kurdish massacres and related outbreaks of starvation and disease.

The British government also attempted to establish a protectorate over Iran, in addition to tightening their control over the increasingly lucrative Persian oil fields.

While Reza Khan and his Cossack brigade secured Tehran, a Persian envoy in Moscow negotiated a treaty with the Bolsheviks for the removal of Soviet troops from Persia.

[26][27][28] However, Reza Shah's later anti-British actions, including fighting and deposing the puppets of the British government in Iran, such as Sheikh Khazal, strongly contradicted these claims.