In the 14th century the tensions between France and England finally snapped and the Hundred Years War was started. There multiple reasons that the French and English declared war on each other. One is that since William the Conqueror had come from Normandy England had had land in France. The French were constantly pushing back against this and there were several fights over the city of Gascony. The second was that Charles IV of France had died without sons or brothers. Edward III of England claimed that the throne should be his since his mother had been Charles IV sister and he was his closest relation. But a ruling in 1316 declared that no woman could have a right to the throne. The French considered Edwards claim invalid because his claim was through his mother who did not have a claim to the throne herself. Instead Charles cousin Phillip became king. At first Edward accepted this but in 1337 Edward III declared war on France. The major three battles in the war at Crecy, Poitiers and Agincourt were decisive English victories but the outcome of the war was a French victory. In the second half of the war with the help of Joan of Arc and Charles VII becoming king of France the French were able to drive the English back. In the Hundred Years War there was not constant fighting. There were periods of 20 years where there was no fighting and if there was actual constant fighting for one hundred years all the soldiers would have been killed.
In the late 14th century was also the Great Western Schism. This was because from 1378 to 1417 there were two popes. The college of Cardinals while electing the pope in 1378 was disturbed by a mob outside declaring that they wanted a Roman pope or at least an Italian. Gregory XI had only just moved the papacy back to Rome from Avignon and the people did not want another French pope that would move the papacy right back to Avignon. Under pressure the Cardinals elected Urban VI to be pope, a cool level headed person to help the tense situation, and an Italian. Soon after his election though Urban VI started behaving erratically and hitting church officials that came to visit him. The cardinals declared the election invalid because they were under duress and elected Clement VII as pope. Urban VI however did not step down and that is how for 39 years there were two popes and two sets of cardinals supporting different people and excommunicating the other side. Finally an ecumenical convinced the two popes to step down and Martin V was declared pope. The result of this schism was a very confusing time and the churches grandeur was greatly diminished.