England followed a somewhat different course of development from the countries on the continent. Being separated from the rest of Europe by the English Channel certainly made it harder to keep in touch with the continent, especially during the Dark Ages. By the same token, the Channel generally has also made it harder to invade England, although that did not seem to be the case against Viking raids and invasions.
After the departure of the Roman legions in the early 400's, the Romano-British population probably carried out resistance against the invading Angles, Saxons, and Jutes (known collectively as the Anglo-Saxons). This resistance is very likely reflected in the legend of King Arthur. However, the Anglo Saxons eventually conquered Britain in the 400's and split it into 7 competing kingdoms known as the Heptarchy. For a brief time, one kingdom or the other might have the upper hand in trying to unite Britain, but the other kingdoms would gang up on that kingdom and restore the balance of power. By 700, the Anglo-Saxons had been converted to Catholic Christianity, and English scholars, led by such men as the Venerable Bede, were in the forefront of European scholarship. However, the advent of Viking raids in the ninth century would radically alter all that.
England especially suffered from the Vikings. Being divided into seven independent kingdoms made it an irresistible target, and Viking raids on England were merciless. Six of the seven Anglo-Saxon kingdoms were overrun, with only Wessex in the south, led by Alfred the Great (871-99), holding on grimly against the Northmen. Alfred did three things to defend his realm against the Vikings. First of all, he kept a standing army, with half of its soldiers on guard at any given time while the other half could tend their crops. Second, he kept a navy to head off Viking invasions and raids before they could even reach English shores. Finally, Alfred established fortified centers, known as burhs, to protect his people and their property from the Vikings.
These measures saved Wessex from Viking conquest, and Alfred and his successors were gradually able to take the offensive and reclaim a good part of England. In a sense, the Viking raids were good for Anglo-Saxon England in two ways. For one thing, they forced the Anglo-Saxons to build a strong state in self-defense. For another thing, the Vikings eliminated the six Anglo-Saxon Kingdoms Wessex had been competing with before. As a result, as Wessex retook one part of Britain after another, a single strong united kingdom replaced seven separate ones. Also, it could more easily impose its own laws and customs on other Saxons, since the Vikings had eliminated the other Saxon kingdoms' laws and customs. Probably reinforcing that trend was the Saxons' fear of the Vikings returning, thus making them more likely to submit to the rule of a strong king. Therefore, the Saxon kings of Wessex could establish a much stronger state than would previously have been possible.
Besides their defense measures, Alfred and his successors did three other things to build a strong English state. First of all, they set up royal officials, known as thegns and reeves, to administer the king's justice throughout his realm. The second thing was to extract a loyalty oath from all Saxon freedmen under their rule. In an age when oaths were taken especially seriously, this was important, since it made loyalty to the king more important than loyalty to any other lord or official. Finally, the Saxon kings collected a permanent tax known as Danegeld. This was originally tribute paid to the Vikings to keep them from raiding. Later, it was used as a defense tax to support the army and navy, thus keeping England safe from attack.
In 973 C.E., a century after Alfred came to the throne, the Church anointed his descendant, Edgar, with oil as God's chosen king of all England. Although the Vikings still controlled much of England under what was known as the Danelaw, this act showed the progress Wessex had made and the ambitions it had toward uniting all of England. Also, by anointing the king as God's chosen, it marked the king as someone special in society and laid the foundations for the later doctrine of Divine Right of Kings.
These measures kept the Saxon state strong until Ethelred "the Unready" (literally "No plan") came to the throne at the age of ten. This triggered renewed Viking raids until the Danish king, Knut, conquered all of England. As luck would have it, when Knut died, his sons fought for the throne, which allowed the Saxons to regain their independence and give the crown to another Saxon king, Edward the Confessor.
However, England was never far from some sort of Viking intervention. In this case, it was the Norman duke, William, who, as a cousin of the childless Edward the Confessor, claimed the English throne when the Saxon king died. When the Saxons chose another Saxon, Harold of Wessex, to succeed Edward, William gathered an army, crossed the channel, and crushed Harold's forces at the Battle of Hastings in 1066 in what would prove to be the last successful invasion of Britain. Despite this, the Anglo-Saxon heritage would continue as the Normans would adopt many of the policies and institutions the Saxons had used to build their state in times of crisis.