In addition, the royal families of England and France were married together in all sorts of peculiar ways, much like the royal houses of all of Europe. Since it was in your interest to marry off one noble child to another noble child, the amount of inbreeding in the European nobility was hardly surprising. In addition, the French of Normandy had conquered England in 1066, and the English nobility was still largely French – in fact, the kings still made addresses in French.
However, it also led to a good deal of squabbling over inheritances.
Chapter 1 : Edward III and the Black Prince
In 1328, Edward III, King of England decided to claim that he stood to legally inherit the throne of France. You see, his mother was the sister of Charles IV (the previous king of France), who had just died. However, the French quoted "Salic Law" and said, essentially, that not only couldn't a woman inherit the throne, that a line of inheritance couldn't pass through a woman. Now, before this point, the actual line of succession wasn't that clear, and Salic law had been invented about a thousand years earlier (named after the Salian Franks of the era), but the fact stood that the French didn't want no stinkin' English king.
In 1337, Edward decided he wasn't going to take this lying down, and refused to bow down to the new French king, Philip VI. He invaded northern France.
At the time, the armored knight ruled the battlefield, and the Black Death was in full swing. So much in full swing, actually, that the English, who had recently landed on the northern shores, and suffering from the Black Death, were looking for a safe haven to chill out at before facing off against the French.
However, the French wanted to get them quickly, and met them at the Battle of Crecy. A force of 30-40,000 troops faced an English army of about 12,000. And were defeated, partially because the English employed a number of longbowmen. The English longbow was a recent innovation, mainly notable for its ability to puncture armor. Up until that point, an armored knight on the battlefield was nearly unkillable – aside from having a horse fall on you or getting bruised to death, it was unlikely that you would receive a wound which would kill you instantly (though of course disease and infection after the battle still killed many).
King Philip died in 1348, and was replaced by his son John II, also called "John the Good".
At any rate, the English continued to dominate the field. Edward's son, later called Edward, the Black Prince, who had shown great bravery at Crecy at the age of only 16, was given command of the English army, and won a staggering victory at the Battle of Poitiers. He added many Welsh archers on to the English army, and was among the first military commanders to give his troops uniforms (partly to make sure that the English knew the Welsh were allies, since they spoke Welsh Gaelic, not English).
In 1360, at the Treaty of Bretigny, the French gave up a lot of land. They pretty much got beat. John the Good was ransomed at three million crowns, and left his son Louis of Anjou as a replacement hostage while he went back to France to raise the money. Louis easily escaped, given that they kept low security, assuming royal honor. John was horrified at this breach of royal ethics, and returned voluntarily to England in 1364 to the great admiration of the citizens and royalty. However, he died a few months later in prison. His eldest son Charles V, also known as Charles the Wise, took power.
Charles V engaged in a great deal of internal building. He constructed the Bastille, restored the Louvre, and built the first royal library in France. In 1369, claiming that Edward had violated the terms of the treaty, he declared war again. The Black Prince was busy in Spain (campaigning for King Pedro the Cruel), and the French made some gains against England. In 1376, the Black Prince died suddenly, leaving his nine-year old son Richard as the heir apparent of England. The next year Edward III died, leaving England with a ten-year old king. The war between England and France largely died down for a while.
Chapter 2 : Henry V & Joan of Arc