EDIT: April Fools, this answer is bullshit. Please do not go and tell your professors how the Hundred Years War was really lost due to strategic goose shortages. They will make fun of you.

According to many scholars, the critical factor is not so much the French ability to recover, but the English capacity to sustain such large field operations. As you probably know, English armies of the period of the period were critical to their military success. Thus, declines in the English capacity to practice archery resulted in a subsequent weakening of English military efforts. It's well known that by the Tudor period, the numbers of English archers had dwindled drastically from the thousands of able bowmen recruited for the Agincourt campaign. There are a number of explanations for this precipitous drop, well attested to by English records of the period.

Firstly, an army made up mostly of archers requires a truly massive amount of arrows to sustain mass volleys for an entire battle. Millions of arrows were produced over the course of the Hundred Years War, which requires huge numbers of goose feathers to be gathered. However, beginning in the 1420s, shortly after the death of Henry V, the goose population of England began to die off in massive numbers. It was known as "goose blight' to contemporaries, but modern experts believe the plague to be a widespread outbreak of renal coccidiosis. The plague, which did not seem to affect humans, had no cure known to the people of late medieval England, who could only stand by and watch as their flocks of geese dies in massive numbers. It was only later on, as Henry VI ordered increased arrow production for the war effort, that the English began to realize how dangerous goose blight was. Armies in France began to lack the arrow reserves necessary to defeat French charges and stop enemy advances. In battles like Patay, Formigne, and Castillon, thousands of archers were cut down after they ran out of ammunition. Driven off the field, the English were forced to remain inside their castles and await French cannons to pound down the walls. Eventually, practically all English holdings except Calais were reconquered by France.

The Wars of the Roses soon distracted the English for the remainder of the 15th century, and they were unable to contest French dominance on the continent. When the domestic political situation had stabilized under the Tudors at the beginning of the 16th century, the goose population had finally stabilized, but was a fraction of the number of geese that had once provided fletches for thousands of arrows. However, it seemed as if the geese were on the road to recovery in the reign of Henry VIII. Alas, it was not to be. A new drug, salvia, was sweeping the youth of Tudor England in the mid-16th century. How salvia, a Mexican plant, got to England is disputed. Some argue that salvia was traded up through the American coast until it reached the Skraelings. The Norse Vinland settlers encountered the plant and brought it back to their own country. Other scholars suggest that salvia was introduced to England by Spanish traders returning from the New World with all manner of strange plants and animals. This theorywould certainly fit in with the major expansion of international trade with England that took place under the Tudors.

How does salvia impact archery, you might ask? The answer is surprisingly simple. Salvia does not grow very well in an English climate and only is able to be produced in the summer months. To preserve stores of such a valuable plant over the winter months, Tudor salvia farmers used goose fat to keep their product safe. Goose poaching skyrocketed in popularity as the common population sought new income sources to deal with rampant price inflation in the period. The increasingly harsh legal penalties for goose poaching did little to deter criminals. The increase in poaching devastated the already marginal goose population. Arrows became increasingly expensive as goose feathers became rarer, which prevented the bulk of the population from practicing archery as much as they had in previous centuries. English commanders of the late Tudor era often complained that their solders were vastly less capable bowmen than previous generations of English archers. The combined havoc wrought by both goose blight and salvia effectively destroyed longbow archery in England, thus critically weakening English field armies until the complete switch to gunpowder in the 1590s.

Edit: This is a fake, don't believe a word. NOT A SINGLE WORD

I would like to add to /u/MI13, because while England was falling apart, France was rebuilding because of their secret weapon, elan.

Elan is one of those words that doesn't translate well into any other language because it's so well known as the word itself. However, a rough translation of it would be bravery.

Yes, Bravery is France's secret weapon. You see, the other people of Europe pale in comparison to the bravery of the French. What other nation could exist from the tip of the bayonet? (Other than Russia). However, this Elan finds itself born out of necessity in the Hundred Years War. In L'Esprit Martial de France by Francois Necker, Necker argues that the French were desperate to stave off the English whom were giving them a hard time. So rather than create better fighters, they created braver fighters. The purpose of this was to scare and overwhelm the generally skilled English soldiers with hordes of brave and sometimes stupid soldiers.

From this, the spirit of French Warfare became surrounded with this concept of elan. With elan, the French could and would overwhelm the entirety of Europe in the coming years. By the French Revolution, France had the bravest and most cunning of soldiers, even if they barely knew how to use anything but their bayonet.

Edit: I held off on this because I wasn't sure but there was another book that I had to find in my library called Bravoure Elevage: Une analyse de l'élan français by Charles Sieyes. In this, he details the efforts of how France bred elan rather than simply sought it.

Charles VIII realized that the only way to stop the English was to outfight them, but due to the specialized nature of the English army, the French couldn't contend on a man by man basis. So due to the generational means of this war, he realized that elan could not only be sought but bred. To ensure that France had only the bravest of the brave, surviving men of extreme courage and valor were bred.

After a battle, those that survived were culled and sorted into sets by large men and overtly brave men. For the sake of breeding, widowed wives were "hired" by the Crown to act as a sort of "brothel" where the lucky few would mate with the women in order to breed the selective traits of brave men.

However, it worked the other way around too, when news came of a woman fighting off an Englishman trying to force himself on her, she would be given a comfortable life on the condition that she would have children for France. Many of these children would bear the last names of brave soldiers but always give the first name of Francois for the country they are tasked to protect.

This history is a little dicey though. The problem with Sieyes is the extremely nationalist historiography that he gives which is questionable at best. However, it seems likely due to the generational warfare that was taking place.

Edit: This is a joke, while elan is a completely real thing, there weren't elan factories.

The English won the Hundred Years War. They got what they wanted, the King of England getting rightful recognition as the King of France.

Then they went and lost it all.

Leaving out the whole front end of the Hundred Years War, in the Treaty of Troyes in 1420, the English recognized Charles VI as King of France and the French recognized King Henry V of England as his heir (cutting Charles VI's son, the Dauphin, out of the succession). This treaty was rather forced on the French by Henry Vs military victories.

In 1422, both Henry V and Charles VI died. At this point, Henry VI, the infant son of Henry V and Charles VI's daughter (the marriage had been another outcome of the Peace at Troyes) became King of England and France - The only English King to actually rule France (not personally, of course, he was an infant).

The Dauphin was upset by this course of events. With the help of Joan of Arc, he rebelled against the Treaty of Troyes and had himself crowned King Charles VII of France in 1429. By 1436 he had re-taken Paris. By 1453, he had driven the English out of all of France except Calais and the Channel Islands (which Islands are today the only French possessions remaining to the English Crown).

If King Henry V had not died of dysentery at the young age of 35, things might have turned out differently.

Still, even with the English handicapped by having an infant King, the Dauphin was doing a terrible job of reclaiming the Throne of France until Joan of Arc came along.

Whatever she did, it might as well have been the divine intervention that she claimed. Her arrival galvanized the French into action, and turned a losing situation into ultimate victory.

She was more than just a symbol or a figure head or a morale booster.

Against the wishes of the strategic leader of the army (Jean d'Orleans) she led soldiers and towns people in four assaults on the ring of bastions and fortresses which the English had erected around Orleans during the siege.

In each of these assaults (during the third of which she had to persuade the mayor of Orleans to open a city gate to let her forces attack after Jean d' Orleans had ordered all the gates locked to prevent further attacks led by Joan) she captured an English bastion.

In the fourth attack, despite being wounded by an arrow in the neck, she succeeded in capturing "Les Tourelles" which was the main English fortification in the siege lines, thus ending the siege of Orleans.

Thereafter, she had the support of the army command and the army advanced towards Reims at her insistence, winning the battle of Patay along the way and capturing many towns.

When the French reached Reims, they crowned the Dauphin King of France, and he went on to reclaim the kingdom.

http://ehistory.osu.edu/osu/archive/hundredyearswar.cfm

http://www.bbc.co.uk/history/british/middle_ages/hundred_years_war_01.shtml

http://web.cn.edu/kwheeler/Hundred_Years.htmlhttp://en.wikipedia.org/wiki/English_claims_to_the_French_throne