High Medieval era

During the reign of the closely related Plantagenet dynasty, which was based in its Angevin Empire, half of France was under Angevin control as well as all of England. However, almost all of the Angevin empire was lost to Philip II of France under Richard the Lionheart, John and Henry III of England. This finally gave the English a separate identity as an Anglo-Saxon people under a Francophone, but not French, crown.

While the English and French had been frequently acrimonious, they had always had a common culture and little fundamental difference in identity. Nationalism had been minimal in days when most wars took place between rival feudal lords on a sub-national scale. The last attempt to unite the two cultures under such lines was probably a failed French-supported rebellion to depose Edward II. It was also during the middle-ages that a Franco-Scottish alliance, known as the Auld Alliance was signed by King John of Scotland and Philip IV of France.

The Hundred Years War

During the Hundred Years War England and France battled for supremacy. Following the Battle of Agincourt the English gained control of vast French territory, but eventually forfeited all claims

The English monarchy increasingly integrated with its subjects and turned to the English language wholeheartedly during the Hundred Years War (1337–1453). Though the war was in principle a mere dispute over territory, it drastically changed societies on both sides of the Channel. The English, although already politically united, for the first time found pride in their language and identity, while the French united politically.

Several of the most famous Anglo-French battles took place in the Hundred Years War: Crécy, Poitiers, Azincourt, Orléans, and Paris. Major sources of French pride stemmed from their leadership during the war. Guesclin was a brilliant tactician who forced the English out of the lands they had procured at the Treaty of Bretigny, a compromising treaty that most Frenchmen saw as a humiliation. Joan of Arc was another unifying figure who to this day represents a combination of religious fervour and French patriotism to all France. After her inspirational victory at Orléans and what many saw as her martyrdom at the hands of treacherous Burgundians and Englishmen, Dunois eventually forced the English out of all of France except Calais, which was only lost in 1558. Apart from setting national identities, the Hundred Years War is often cited as the root of the traditional rivalry and at times hatred between the two countries.

During this era, the English lost their last territories in France, except Calais, though the English monarchs continued to style themselves as Kings of France until 1800.

The early modern period

Henry VIII and Francis I met at the Field of the Cloth of Gold in 1519, briefly marking a period of détente between the two nations

The English and French were engaged in numerous wars in the following centuries. They took opposite sides in all of the Italian Wars (1494–1559).

An even deeper division set in during the Reformation, when most of England converted to Protestantism and France remained Roman Catholic. This enabled each side to see the other as not only a foreign evil but also a heretical one. In both countries there was intense civil religious conflict. During the oppression of the Roman Catholic Louis XIII of France, many Protestant Huguenots fled to England. Similarly, many Catholics fled from England to France.

Henry VIII of England had initially sought an alliance with France, and the Field of the Cloth of Gold saw a face to face meeting between him and King Francis I of France.