Anglo-Norman warfare was characterised by attritional military campaigns, in which commanders tried to raid enemy lands and seize castles in order to allow them to take control of their adversaries' territory, ultimately winning slow but strategic victories. Pitched battles were occasionally fought between armies but these were considered risky engagements and usually avoided by prudent commanders. The armies of the period comprised bodies of mounted, armoured knights, supported by infantry. Crossbowmen become more numerous in the 12th century, alongside the older shortbow. At the heart of these armies was the "familia regis", the permanent military household of the king, which was supported in war by feudal levies, drawn up by local nobles for a limited period of service during a campaign. Mercenaries were increasingly employed, driving up the cost of warfare considerably, and adequate supplies of ready cash became essential for the success of campaigns.