Many tensions existed within the system of government. Royal landownings and wealth stretched across England, and placed the king in a privileged position above even the most powerful of the noble elite. Successive kings, though, still needed more resources to pay for military campaigns, conduct building programmes or to reward their followers, and this meant exercising their feudal rights to interfere in the land-holdings of nobles. This was contentious and a frequent issue of complaint, as there was a growing belief that land should be held by hereditary right, not through the favour of the king. Property and wealth became increasingly focused in the hands of a subset of the nobility, the great magnates, at the expense of the wider baronage, encouraging the breakdown of some aspects of local feudalism. As time went by, the Norman nobility intermarried with many of the great Anglo-Saxon families, and the links with the Duchy began to weaken. By the late 12th century, mobilising the English barons to fight on the continent was proving difficult, and John's attempts to do so ended in civil war. Civil strife re-emerged under Henry III, with the rebel barons in 1258–59 demanding widespread reforms, and an early version of Parliament was summoned in 1265 to represent the rebel interests.