Acting on occasion as kingmakers, this force played a pivotal role in modern Iranian history during the Persian Constitutional Revolution, the rise of Reza Shah, and the foundation of the Pahlavi dynasty.

Together with a Swedish-trained and officered gendarmerie, the Cossack Brigade came to comprise the most effective military force available to the Iranian crown in the years prior to World War I.

The Cossack regiments of the Imperial Russian Army were based on a feudal-style system under which military service was given in return for long-term grants of land.

The initial strength of the brigade was 400 men drawn from immigrants known as Caucasian muhajirs, who were descendants of Circassians and Transcaucasian Muslims who had migrated to Iran to avoid Russian rule.

Domantovich made rapid progress with their training and the Shah ordered the strength of the new brigade to be increased to 600 men drawn from the regular army.

The rapid progress of the Cossack Brigade caused concern in Russia due to the fear that it might become a true fighting force rather than a tool of the Russian government.

By this time the brigade was rapidly disintegrating and the Shah was under pressure to disband it and give control over army training to German military advisors.

The Muhajir faction mutinied in 1895, dividing the brigade and seizing a large portion of its funds, encouraged by the Shah's son who was Minister of War.

Nayeb os-Saltenah, the local commander of the forces in Tehran was likely to seize power from the legitimate heir, Mozaffar ad-Din Shah, who was in Tabriz.

Kosagovski, backed by the brigade, the Russians and British, warned Saltenah that only Mozaffar ad-Din Shah would be recognized as the legitimate heir.

The brigade on this date established themselves as kingmakers and in the future would serve as important tools for both the Russians and the Shah in maintaining control of Iran.

Russian influence inside Iran expanded tremendously as the brigade was able to exert massive control in internal Iranian politics and intrigues.

As the brigade was numerically enlarging and drastically growing in military strength, eventually civilian volunteers were also accepted into its ranks, including members of ethnic and religious minorities.

This proportion of officers to other ranks was far higher than the one to thirty ratio that was usual in armies of that period and was regarded with concern by contemporary British commentators, who noted that the brigade was effectively under the direct control of the Imperial Russian Legation in Tehran.

[5] The second major event the Cossack Brigade played a role in was the 1906 Constitutional Revolution, as a result of intense political pressure and rebellion.

He was briefly successful and with the help of Colonel Liakhov, the brigade commander, he governed Tehran for a year acting as a military dictator.

This was an important transition point in the history of the brigade as it now came under complete British and Iranian control and was effectively purged of Russian influence.

It is in this context of fragmentation and disorder that Reza Khan, an officer from the Cossack Brigade, rose to power as Iran's "man on horseback" who would save the country from chaos.

[7] About a month later, under British direction, Reza Khan led his 3,000–4,000 strong detachment of the Cossack Brigade based in Qazvin and Hamadan to Tehran in 1921 and seized the capital.

With his expanded forces and the Cossack Brigade, Reza Khan launched military actions to eliminate separatist and dissident movements in Tabriz, Mashhad, and the Jangalis in Gilan, Simko and the Kurds.