Colonial expansion.--Nevertheless, the frontiers of the Spanish colonies slowly expanded, and slowly Spain extended her laws, her language, and her faith over lands and tribes more and more remote from the Mexican capital, the struggle with the natives becoming sterner at each step in advance. In the course of the seventeenth century northern Sinaloa and Sonora were colonized; permanent missionary occupation, after many failures, was effected in Lower California; southern, western, and eastern Chihuahua were settled; the new province of Coahuila was established athwart the Rio Grande, and a new and flourishing missionary district was opened in western Florida. In the course of the century the Spanish colonial frontiers began to clash with those of France and England, on the mainland now as well as in the islands, and there ensued a series of border struggles, all a part of the international conflict for the continent. To restrain the encroaching French and English, Texas was occupied temporarily and Pensacola permanently. The principal setbacks on the borders were the loss of Jamaica to England (1655), the contraction of the Florida frontier through the founding of Virginia and the Carolinas, and the temporary loss of New Mexico through the Pueblo Revolt in 1680. Thus the Spanish frontier line swung round as on a pivot, the gains in the west being partly offset by the losses in the east. Meanwhile the English, French, and Dutch occupied most of the lesser islands of the Caribbean, which had been neglected by Spain. At the same time, Spain's hold on her colonial commerce became more and more precarious through the encroachments of her national enemies. FRONTIER ADMINISTRATION The governors.--The old days of the _adelantados_, with unlimited powers, had passed, and the royal arm now reached the farthest outposts. The secular government of the frontier provinces was almost wholly military. A few villas or towns had their elective _cabildos_, or town councils, and a modicum of self government. The official heads of the provinces were the governors, who held office by royal appointment; _ad interim_ governors might be appointed by the viceroys. Governors, like other prominent officials, frequently purchased their offices, a practice not confined at that time to Spanish America. The governor was also _capitán general_ of his province, and his capital was usually at the principal presidio or garrison. In these capacities he exercised both civil and military authority. Under the governors there were usually lieutenant-governors in the sub-districts, who as a rule commanded the troops of some presidio.