France
Summary
The Hundred Years War dominates the history of France during these two centuries. Up to 1337, we see a series of short reigns that introduced few changes, then the failure of the Capetian line and the beginning of the Valois that contributed to the outbreak of the war. France itself was undergoing change, though, and had been since the late 1200s. Economic strains, changes in climate, demographic stress, and then plague, these alone would have been enough to challenge any monarchy. Couple these with a devastating war and France's story is a tale of woe for a full century.
With Charles VII, though, France began a slow recovery that bore spectacular fruit. With two strong and long-reigning kings in Charles VII and Louis XI, the French monarchy recovered its former glory and in the process created a new governmental bureaucracy that proved equal to the new reality of expensive armies and far-flung foreign policies. They tamed, though did not yet break, their powerful nobles and made the crown by far the richest and strongest among them. After war, civil war, plague and famine, France was again among the leading nations of Europe.