The period after the Norman conquest up until about 1485 is called the Middle Ages (or the medieval period). It was a time of almost constant war.
The English Kings fought with the Welsh, Scottish and Irish noblemen for control of their lands. In Wales, the English were able to establish their rule. In 1284 King Edward I of England introduced the statute of Rhuddlan, which annexed Wales to the Crown of England. Huge castles, including Conwy and Caernarvon, were built to maintain this power. By the middle of the 15th century the last Welsh rebellions had been defeated. English laws and the English language were introduced.
In Scotland, the English Kings were less successful. In 1314 the Scottish, led by Robert the Bruce, defeated the English at the battle of Bannockburn, and Scotland remained unconquered by the English.
At the beginning of the Middle Ages, Ireland was an independent country. The English first went to Ireland as stoops to help the Irish king and remained to build their own settlement. By 1200, the English ruled an area of Ireland known as the Pale, around Dublin. Some of the important lords in other parts of Ireland accepted the authority of the English king.
During the Middle Ages, the English kings also fought a number of wars abroad. Many Knights took part in the Crusades, in which European Christians fought for control of the Holy Land. English kings also fought a long war with France, called the Hundred Years War (even though it actually lasted 116 years). One of the most famous battles of the Hundred Years War was the battle of Agincourt in 1415, where King Henry V's vastly outnumbered English army defeated the French. The English left France in the1450s.