From the commencement of his reign he found himself involved in disputes with Ranjit Singh, the Sikh ruler of the Punjab region, who used the dethroned Sadozai prince, Shah Shujah Durrani, as his instrument. In 1834 Shah Shujah made a last attempt to recover his kingdom. He was defeated by Dost Mohammad Khan under the walls of Kandahar, but Ranjit Singh seized the opportunity to annex Peshawar. Dost Mohammad sent his son Akbar Khan to defeat the Sikhs at the Battle of Jamrud in 1837. His failure in recapturing the Jamrud Fort became the Afghan Amir's worst concern.