Radama's successor, Queen Ranavalona I (1828–61), responded to increasing political and cultural encroachment on the part of Britain and France by issuing a royal edict prohibiting the practice of Christianity in Madagascar and pressuring most foreigners to leave the territory. William Ellis (missionary) described his visits made during her reign in his book ''Three Visits to Madagascar during the years 1853, 1854, and 1856''. The Queen made heavy use of the traditional practice of ''fanompoana'' (forced labor as tax payment) to complete public works projects and develop a standing army of between 20,000 and 30,000 Merina soldiers, whom she deployed to pacify outlying regions of the island and further expand the Kingdom of Merina to encompass most of Madagascar. Residents of Madagascar could accuse one another of various crimes, including theft, Christianity and especially witchcraft, for which the ordeal of ''tangena'' was routinely obligatory. Between 1828 and 1861, the ''tangena'' ordeal caused about 3,000 deaths annually. In 1838, it was estimated that as many as 100,000 people in Imerina died as a result of the tangena ordeal, constituting roughly 20 percent of the population. The combination of regular warfare, disease, difficult forced labor, and harsh measures of justice resulted in a high mortality rate among soldiers and civilians alike during her 33-year reign, the population of Madagascar is estimated to have declined from around 5 million to 2.5 million between 1833 and 1839.