 Complete the following phrase:  On 14 January 1921, the commander of the British Forces in Iran, General Edmund Tiny Ironside, promoted Reza Khan, who had been leading the Tabriz battalion, to lead the entire brigade. About a month later, under British direction, Reza Khan led his 3,000-4,000 strong detachment of the Cossack Brigade, based in Niyarak, Qazvin, and Hamadan, to Tehran and 