Christian missionaries like David Cargill also arrived in the 1830s from recently converted regions such as Tonga and Tahiti, and by 1840 the European settlement at Levuka had grown to about 40 houses with former whaler David Whippey being a notable resident. The religious conversion of the Fijians was a gradual process which was observed first-hand by Captain Charles Wilkes of the United States Exploring Expedition. Wilkes wrote that "all the chiefs seemed to look upon Christianity as a change in which they had much to lose and little to gain". Christianised Fijians, in addition to forsaking their spiritual beliefs, were pressured into cutting their hair short, adopting the sulu form of dress from Tonga and fundamentally changing their marriage and funeral traditions. This process of enforced cultural change was called ''lotu''. Intensification of conflict between the cultures increased, and Wilkes was involved in organising a large punitive expedition against the people of Malolo. He ordered an attack with rockets which acted as makeshift incendiary devices. The village, with the occupants trapped inside, quickly became an inferno with Wilkes noting that the "shouts of men were intermingled with the cries and shrieks of the women and children" as they burnt to death. Wilkes demanded the survivors should "sue for mercy" and if not "they must expect to be exterminated". Around 57 to 87 Maloloan people were killed in this encounter.