Middle Ages
Throughout the 14th century, French kings sought to expand their influence at the expense of the territorial holdings of the nobility. They ran into difficulties when attempting to confiscate the holdings of the English kings in southern France, leading to the Hundred Years' War, waged from 1337 to 1453. Early in the war the English under Edward III (r. 1327–77) and his son Edward, the Black Prince (d. 1376), won the battles of Crécy and Poitiers, captured the city of Calais, and won control of much of France. The resulting stresses almost caused the disintegration of the French kingdom during the early years of the war. In the early 15th century, France again came close to dissolving, but in the late 1420s the military successes of Joan of Arc (d. 1431) led to the victory of the French and the capture of the last English possessions in southern France in 1453. The price was high, as the population of France at the end of the Wars was likely half what it had been at the start of the conflict. Conversely, the Wars had a positive effect on English national identity, doing much to fuse the various local identities into a national English ideal. The conflict with France also helped create a national culture in England separate from French culture, which had previously been the dominant influence. The dominance of the English longbow began during early stages of the Hundred Years' War, and cannon appeared on the battlefield at Crécy in 1346.
1340s
In Europe, the decade continued the period of gradual economic decline, often mistitled the "depression" of the 1340s. This followed the end of the Medieval Warm Period and the start of the Little Ice Age in the 1300s, and affected most of Western Europe, with the exception of a few Italian city-states. The state increasingly interfered in the social and economic life of the decade, while Europe entered a period which saw almost continuous war for the next century. The Hundred Years' War (1337–1453) between France and England continued, and Edward III of England led an invasion resulting in notable victories at the Battles of Sluys and Crécy in 1340 and 1346 respectively. The medieval crusading spirit continued in Spain, with a Castilian victory at the Battle of Río Salado and the recommencement of the Reconquista in 1340; and in the Baltic, with King Magnus II of Sweden's Northern Crusades against Novgorod in 1347–1348. In the east, the Byzantine Empire, then under the Palaiologoi, saw the start of the disastrous Byzantine civil war of 1341–47. Meanwhile, a crisis of confidence in the Florentine banks caused many of them to collapse between 1341 and 1346. The Black Plague which struck Europe in 1348 wiped out a full third of the population by the end of the decade.