as for their military accomplishments and innovations. Norman adventurers established a kingdom in Sicily and southern Italy by conquest, and a Norman expedition on behalf of their duke led to the Norman Conquest of England. Norman influence spread from these new centres to the Crusader States in the Near East, to Scotland and Wales in Great Britain, and to Ireland. Relations between the major powers in Western society: the nobility, monarchy and clergy, sometimes produced conflict. If a monarch attempted to challenge church power, condemnation from the church could mean a total loss of support among the nobles, peasants, and other monarchs. Holy Roman Emperor Henry IV, one of the most powerful men of the 11th century, stood three days bare-headed in the snow at Canossa in 1077, in order to reverse his excommunication by Pope Gregory VII. As monarchies centralized their power as the Middle Ages progressed, nobles tried to maintain their own authority. The sophisticated Court of Holy Roman Emperor Frederick II was based in Sicily, where Norman, Byzantine, and Islamic civilization had intermingled. His realm stretched through Southern Italy, through Germany and in 1229, he crowned himself King of Jerusalem. His reign saw tension and rivalry with the Papacy over control of Northern Italy. A patron of education, Frederick founded the University of Naples. Plantagenet kings first ruled the Kingdom of England in the 12th century. Henry V left his mark with a famous victory against larger numbers at the Battle of Agincourt, while Richard the Lionheart, who had earlier distinguished himself in the Third Crusade, was later romanticised as an iconic figure in English folklore. A distinctive English culture emerged under the Plantagenets, encouraged by some of the monarchs who were patrons of the "father of English poetry", Geoffrey Chaucer. The Gothic architecture style was popular during the time, with buildings such as Westminster Abbey remodelled in that style. King John's sealing of the Magna Carta was influential in the development of common law and constitutional law. The 1215 Charter required the King to proclaim certain liberties, and accept that his will was not arbitrary — for example by explicitly accepting that no "freeman" (non-serf) could be punished except through the law of the land, a right which is still in existence today. Political institutions such as the Parliament of England and the Model Parliament originate from the Plantagenet period, as do educational institutions including the