At the end of 1647 Khmelnytsky reached the estuary of the Dnieper river. On 7 December, his small detachment (300–500 men), with the help of registered Cossacks who went over to his side, disarmed the small Polish detachment guarding the area and took over the Zaporozhian Sich. The Poles attempted to retake the Sich but were decisively defeated as more registered Cossacks joined the forces. At the end of January 1648, a Cossack Rada was called and Khmelnytsky was unanimously elected a hetman. A period of feverish activity followed. Cossacks were sent with hetman's letters to many regions of Ukraine calling on Cossacks and Orthodox peasants to join the rebellion, Khortytsia was fortified, efforts were made to acquire and make weapons and ammunition, and emissaries were sent to the Khan of Crimea, İslâm III Giray.