attempts to systematise and codify the law and the beginnings of an educated professional body of lawyers. In the Late Middle Ages major institutions of government, including the privy council and parliament developed. The council emerged as a full-time body in the fifteenth century, increasingly dominated by laymen and critical to the administration of justice. Parliament also emerged as a major legal institution, gaining an oversight of taxation and policy. By the end of the era it was sitting almost every year, partly because of the frequent minorities and regencies of the period, which may have prevented it from being sidelined by the monarchy. Warfare In the Early Middle Ages, war on land was characterised by the use of small war-bands of household troops often engaging in raids and low level warfare. The arrival of the Vikings brought a new scale of naval warfare, with rapid movement based around the Viking longship. The birlinn, which developed from the longship, became a major factor in warfare in the Highlands and Islands. By the High Middle Ages, the kings of Scotland could command forces of tens of thousands of men for short periods as part of the "common army", mainly of poorly armoured spear and bowmen. After the introduction of feudalism to Scotland, these forces were augmented by small numbers of mounted and heavily armoured knights. Feudalism also introduced castles into the country, originally simple wooden motte-and-bailey constructions, but these were replaced in the thirteenth century with more formidable stone "enceinte" castles, with high encircling walls. In the thirteenth century the threat of Scandinavian naval power subsided and the kings of Scotland were able to use naval forces to help subdue the Highlands and Islands. Scottish field armies rarely managed to stand up to the usually larger and more professional armies produced by England, but they were used to good effect by Robert I at Bannockburn in 1314 to secure Scottish independence. He also made use of naval power to support his forces and began to develop a royal Scottish naval force. Under the Stewart kings these forces were further augmented by specialist troops, particularly men-at-arms and archers, hired by bonds of manrent, similar to English indentures of the same period. New "livery and maintenance" castles were built to house these troops and castles began to be adapted to accommodate gunpowder weapons. The Stewarts also adopted major innovations in continental warfare, such