According to Madagascar historian Gwyn Campbell, the number of non-Merina who died in violent conflict during the military campaigns of Ranavalona and her predecessor Radama from 1816 to 1853 was estimated at about 60,000. Additionally, a considerable proportion of the population not killed in battle in the subjugated provinces eventually died from famine as a consequence of scorched earth policies. Deaths among the Merina soldiers engaged in military actions were also high, estimated at about 160,000 for the period 1820–1853. A further 25–50% of the queen's soldiers stationed in lowland areas were estimated to have died each year due to diseases such as malaria. Although prevalent in the coastal parts of the island, malaria was uncommon in the high-altitude zone around Antananarivo, and Merina soldiers possessed little natural resistance against it. An average of 4,500 soldiers died each year for the greater part of Ranavalona's reign, contributing to severe depopulation in Imerina.