Poor harvests had already brought hardship by the 1290s but there were even more bad years at the beginning of the new century and in a disastrous series of wet summers in 1315, 1316 and 1317 caused a famine. At least half a million people died; and land sales on an unprecedented scale combined with a crime wave, are clear evidence of social distress. In some places the population recovered after the Great Famine but numbers usually stagnated or declined. By 1340 much land in the midlands lay uncultivated and reclaimed wetlands on the south and east coasts were being invaded by the sea. In 1348 - 1349 the Black Death killed about half of the population. These were not just a series of unfortunate accidents caused by bad weather and the arrival of a new bacteria. Growth was ending before the disasters - land was no longer available on a large scale and after reaching a peak in 1300 AD, the volume of trade began to shrink. New towns and markets were no longer being founded. When the famine came it struck an already undernourished population. Prosperous, confident societies recover from natural disasters. The crises of the 14th Century exposed the principle weakness of Medieval development - it had left millions of smallholders in the country and the laborers in the towns who could hope to earn no more than 30 shillings in a year and that was not enough to support a family. They could make ends meet in good years with wives and children contributing to their earnings but any large rise in the price of grain threatened their lives. Had the Black Death been a simple outbreak of disease, there would have been rapid recovery; instead the plague recurred in the 1360s and there seems to have been no sustained rise in births to replace the losses.
Various explanations have been offered for this reversal of fortunes. It is argued that the commercial growth which had sustained the expansion ended because the market was glutted: in other words, that society which could support an urban proportion of roughly 20% and no more, and that only a further rise in productivity could break the impasse; that was not forthcoming. Alternatively, it is suggested that the problem was associated with an over-extension of cultivation which had taken in poor land and had caused imbalances between pastoral and arable farming, to the detriment of grain crops deprived of fertilization. On the other hand, technical solutions could have been found for such problems and the recession was not confined to arable - it hit regions specializing in pastoral farming. Perhaps, in that case, the high level of rents prevented the peasants from escaping from the trap of low productivity. Or perhaps the heavy taxation from the 1290s added a last straw to the burden of rent. Or perhaps society had become too hierarchical with the urban and rural elites holding back more enterprising spirits. Or as a final possibility, could the aristocrats have served as unproductive role models, encouraging the rest of society to spend rather than invest?
It is hard to form a clear answer. It is a search for explanations of a complex social malaise which affected the whole of western Europe and which lasted for more than a century. The crisis must be compared in the complexity of its causes with the fall of the Roman Empire in the 5th Century.