The origins of trade unions can be traced back to 18th century Britain, where the rapid expansion of industrial society then taking place drew women, children, rural workers and immigrants into the work force in large numbers and in new roles. They encountered a large hostility in their early existence from employers and government groups; at the time, unions and unionists were regularly prosecuted under various restraint of trade and conspiracy statutes. This pool of unskilled and semi-skilled labour spontaneously organized in fits and starts throughout its beginnings, and would later be an important arena for the development of trade unions. Trade unions have sometimes been seen as successors to the guilds of medieval Europe, though the relationship between the two is disputed, as the masters of the guilds employed workers (apprentices and journeymen) who were not allowed to organize.