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.