They travelled into an unknown wilderness, though usually escorted by modest military detachments. They had to select a place for a mission, collect a group of natives who had different customs and language, get them involved enough to help build mission structures, collect more natives, teach them Christianity, farming, ranching, weaving, blacksmithing, etc. All this had to be done in a climate notable for its violence, and under threat of Indian attack Most of the missionaries died at the missions after many years of steadfast, and mostly successful activity.

Spanish treatment of the Indians was by no means always benign. Coercion was sometimes employed to round up neophytes for the missions, and once there, they were sometimes employed on something like a slave labor basis. However, as an American, and especially as a Texan, I am in no position to throw rocks in this particular greenhouse. Texans, in particular used annihilation, supplemented by expulsion in dealing with the native population. The Spanish record is rather good, by that standard.