On 23 July 1839, in a surprise attack, the British-led forces captured the fortress of Ghazni, which overlooks a plain leading eastward into the Khyber Pakhtunkhwa. The British troops blew up one city gate and marched into the city in a euphoric mood. During the battle, the British suffered 200 killed and wounded, while the Afghans suffered 500 killed and 1,500 captured. Ghazni was well-supplied, which eased the further advance considerably.

Following this and an uprising of Tajiks in Istalif, the British marched to Kabul with no resistance from Dost Mohammad's troops. With his situation rapidly deteriorating, Dost Mohammed offered to accept Shuja as his overlord in exchange for becoming his wazir (a common practice in Pashtunwali), which was promptly turned down. In August 1839, after thirty years, Shuja was again enthroned in Kabul. Shuja promptly confirmed his reputation for cruelty by seeking to wreak vengeance on all who had crossed him as he considered his own people to be "dogs" who needed to be taught to obey their master.