In 1841, during the Sikh civil war, Ranjit Singh's son, Sher Singh, used the Mosque's large minarets for placement of zamburahs or light guns, which were placed atop the minarets to bombard the supporters of the Sikh Maharani Chand Kaur taking refuge in the besieged Lahore Fort, inflicting great damage to the Fort itself. In one of these bombardments, the Fort's Diwan-e-Aam (Hall of Public Audience) was destroyed (it was subsequently rebuilt by the British but never regained its original architectural splendour). During this time, Henri De la Rouche, a French cavalry officer employed in the army of Sher Singh, used a tunnel connecting the Badshahi Mosque to the Lahore Fort to temporarily store gunpowder. When the British took control of India, they continued the Sikh practice of using the Mosque and the adjoining Fort as a military garrison. The 80 cells (hujras) built into the walls surrounding the Mosque's vast courtyard on three sides were originally study rooms, which were used by the Sikhs under Ranjit Singh to house troops and military stores. The British demolished them so as to prevent them from being used for anti-British activities and rebuilt them to form open arcades or dalans, which continue to this day. Sensing increasing Muslim resentment against the use of the Mosque as a military garrison, which was continuing since Sikh Rule, the British set up the Badshahi Mosque Authority in 1852 to oversee the restoration and return of the Mosque to Muslims as a place of religious worship. From 1852 onwards, piecemeal repairs were carried out under the supervision of the Badshahi Mosque Authority. Extensive repairs commenced from 1939 onwards. The blueprint for the repairs was prepared by the architect Nawab Zen Yar Jang Bahadur.