using irrigation in agriculture and encouragement of economic activity, the nobility never really produced anyone that could bring about serious reforms. Charles, on becoming king, clashed with his nobles during the Castilian War of the Communities when he attempted to fill government positions with effective Dutch and Flemish officials. Philip II encountered major resistance when he tried to enforce his authority over the Netherlands, contributing to the rebellion in that country. The Count-Duke of Olivares, Philip IV's chief minister, always regarded it as essential to Spain's survival that the bureaucracy be centralized; Olivares even backed the full union of Portugal with Spain, though he never had an opportunity to realize his ideas. The bureaucracy became so increasingly bloated and corrupt that by the time of Olivares's dismissal in 1643, its deterioration had rendered it largely ineffective. Economy Like most of Europe, Spain had suffered from famine and plague during the 14th and 15th centuries. By 1500, Europe was beginning to emerge from these demographic disasters, and populations began to explode. Seville, which was home to 60,000 people in 1500 burgeoned to 150,000 by the end of the century. There was a substantial movement to the cities of Spain to capitalize on new opportunities as shipbuilders and merchants to service Spain's impressive and growing empire. The 16th century was a time of development in Spain as both agriculture and trade burgeoned. Throughout the harsh interior of Castile grain and wool production grew. The former fed an expansion of the population. The latter fed both local textile manufacturing and a lucrative trade with the Netherlands. The Castilian cities of Burgos, Segovia, Cuenca and Toledo, flourished with the expansion of the textile and metallurgical industries. Santander, on the northern Atlantic coast, grew in wealth from its traditional roles as a port linking the country's interior with Northern Europe and as a ship building centre. Southern cities like Cádiz and Seville expanded rapidly from the commerce and shipbuilding spurred on by the demands of the American colonies. Barcelona, already one of Europe's most important and sophisticated trading port cities in the Middle Ages, continued to develop. By 1590, Spain's population was far greater than what it had been in any previous period. It was during this last decade when Castile began to suffer crop failures and was struck by a plague from 1596 that brought about the first serious reversal in population numbers; a