Medieval warfare in the period 1000-1300 was influenced more than anything else by the nature of the people waging war, by the climate and geographical circumstances in which they fought, and by the available technology, which itself was also in part governed by political and social factors. War was the instrument of landed proprietors because land was the primary source of wealth, and power over men and women sprang from ownership of it. Kings and emperors claimed a special authority but generally lacked the means to make it real: they too were primarily influential as owners of land. It was the needs of a landowning elite which gave rise to the characteristic institutions of medieval warfare, the castle and the knight. These were guarantees of their social domination over the masses who worked the land, title deeds to impress rivals and bargaining-counters in the business of power-broking. Since states were rudimentary, and in major areas never really developed, the ability - or at least the potential - to wage war was a vital factor in political life. Castles and armed followings were the currency of political influence and those without them served, at best, as followers.
The noble's armed retinue were the guarantee of his social position and political influence. They were so fundamental to his being that when armies gathered, considerations of rank, based on differences in landholding, dictated command structures. Armies were collections of personal retinues centred on the following of the commander. The sheer cost of war meant that nobody could afford to maintain regular standing forces, and it is doubtful whether political circumstance would have permitted it if it had been possible. Richard I seems to have wanted a regular army of 300 knights supported by taxation, but this sank without trace. Any such development would have struck at the influence of the great. It was not that the leaders of society necessarily wished to be soldiers themselves, but they knew that so much influence