In 1891, Johnston only controlled a fraction of the Shire Highlands, itself a small part of the whole protectorate, and initially had a force of only 70 Indian troops to impose British rule. These troops, later reinforced by Indian and African recruits, were used up to 1895 to fight several small wars against those unwilling to give up their independence. After this, until 1898, troops were used to assist the locally recruited police force to suppress the slave trade. The three main groups resisting British occupation were Yao chiefs in the south of the protectorate and Swahili groups around the centre and north of Lake Nyasa, both involved in the slave trade, and Ngoni people who had formed two aggressively expansionists kingdoms in the west and north.