13. You Would Fight at Certain Times of the Year
From the fall of the Roman Empire through the Medieval era, there were very few standing armies in which career soldiers fought year-round (an exception is the Knights Templar). Many soldiers were first and foremost farmers and peasants, especially foot soldiers who had no horses. They had to carry out their duties in the fields, or else they and everyone else in the village would starve. As such, there were certain seasons in which lords and kings would call upon their people to go into battle or embark on some other military campaign. Charlemagne was known to urge people to arms during the spring, once they had completed planting for the year.
Campaign season was usually between planting and harvest, often during the summer months. Soldiers preferred not to have to march into battle during the cold winter months, especially not when wearing over a hundred pounds of armor and chain mail. None of that is to say that fighting only occurred during the summer. Sieges could often last for weeks and extend well into the winter. These sieges were particularly destructive, as they often prohibited people from being able to harvest the year’s food and therefore led to mass starvation.