The Battle of Crcy took place on 26 August 1346 in northern France between a French army commanded by King Philip VI and an English army led by King Edward III. The French attacked the English while they were traversing northern France during the Hundred Years' War, resulting in an English victory and heavy loss of life among the French.

The English army had landed in the Cotentin Peninsula on 12 July. It had burnt a path of destruction through some of the richest lands in France to within 2 miles (3 km) of Paris, sacking many towns on the way. The English then marched north, hoping to link up with an allied Flemish army which had invaded from Flanders. Hearing that the Flemish had turned back, and having temporarily outdistanced the pursuing French, Edward had his army prepare a defensive position on a hillside near Crcy-en-Ponthieu. Late on 26 August the French army, which greatly outnumbered the English, attacked.

During a brief archery duel a large force of French mercenary crossbowmen was routed by Welsh and English longbowmen. The French then launched a series of cavalry charges by their mounted knights. These were disordered by their impromptu nature, by having to force their way through the fleeing crossbowmen, by the muddy ground, by having to charge uphill, and by the pits dug by the English. The attacks were further broken up by the effective fire from the English archers, which caused heavy casualties. By the time the French charges reached the English men-at-arms, who had dismounted for the battle, they had lost much of their impetus. The ensuing hand-to-hand combat was described as "murderous, without pity, cruel, and very horrible." The French charges continued late into the night, all with the same result: fierce fighting followed by a French repulse.

The English then laid siege to the port of Calais. The battle crippled the French army's ability to relieve the siege; the town fell to the English the following year and remained under English rule for more than two centuries, until 1558. Crcy established the effectiveness of the longbow as a dominant weapon on the Western European battlefield.

The Hundred Years' War (French: La guerre de Cent Ans; Picard: Dgère d'Un Chint Ans; 1337–1453) was a series of armed conflicts between the kingdoms of England and France during the Late Middle Ages. It originated from disputed claims to the French throne between the English royal House of Plantagenet and the French royal House of Valois. Over time, the war grew into a broader power struggle involving factions from across Western Europe, fueled by emerging nationalism on both sides.

The Hundred Years' War was one of the most significant conflicts of the Middle Ages. For 116 years, interrupted by several truces, five generations of kings from two rival dynasties fought for the throne of the largest kingdom in Western Europe. The war's effect on European history was lasting. Both sides produced innovations in military technology and tactics, including professional standing armies and artillery, that permanently changed warfare in Europe; chivalry, which had reached its height during the conflict, subsequently declined. Stronger national identities took root in both countries, which became more centralised and gradually rose as global powers.The term "Hundred Years' War" was adopted by later historians as a historiographical periodisation to encompass related conflicts, constructing the longest military conflict in European history. The war is commonly divided into three phases separated by truces: the Edwardian War (1337–1360), the Caroline War (1369–1389), and the Lancastrian War (1415–1453). Each side drew many allies into the conflict, with English forces initially prevailing; the House of Valois ultimately retained control over France, with the previously-intertwined French and English monarchies thereafter remaining separate.