Rentap's fort was formidable as it was surrounded on all sides by steep cliff, and the walls were made of vertical iron wood (Tebelian) planks which could not be penetrated by rifle shots. Within the fort, Rentap's warriors had built a platform from which they could shoot at a narrow backbone of rock which was the only approach to the fort. Rentap also had muskets, small cannons and a swivel-gun (captured when Alan Lee was killed at the Battle of Lintang Batang in 1853).