he hill-fort of Nandidrug lies 31 miles North of Bangalore and 4,881 ft above sea level. The perpendicular sides of the rock are 1,500 ft high, and its double line of ramparts were thought by Tipu and Haidar to render the fort impregnable. Wilks emphasises the steadiness and skill required by any assailants in working up the craggy face, and dragging cannon to the batteries , and Dirom declared that 'the exertions required to form a gun road and erect batteries on the face of this mountain surpassed whatever had been known in any former siege in India.' It not only held a commanding position in the area, but whilst in Tipu's hands, it blocked the British line of communication to Goorumconda and the Nizam's army.

The rising of the moon on the night of 18 October 1791 was decreed by Lord Cornwallis, the British Commander in Chief, to be the signal for the assault. The watchful occupants immediately illuminated the fort with blue lights, and showered down large stones and fire from 17 pieces of large-calibre cannon. Despite the 'extraordinary obstacles, both of nature and art' which Lord Cornwallis acknowledged in his congratulatory letter to his troops (19th October 1791), the fort was invested, with a loss of only 40 Europeans and 81 sepoys and pioneers killed or wounded.