Quote Originally Posted by EatYerGreens
I only brought that up after the "men available for 40 days per year" thing was mentioned and I'd speculated that this was due to weather considerations. Classic example of weather working against a side which the odds say should have won. Admittedly off topic, so apologies for that.
OT-warning

I wanted to continue discussing your example: there wasn't so much as a fighting season, it just was that the king had a right to summon his feudal levies for forty days a year, any forty days a year. If he needed them longer, he had to pay. And this quite often happened the French kings during the hundred years war (when they were chasing the smaller English armies around until the English found a good hill and let the French storm themselves to death), so it was not really weather-dependent. The idea is just that the feudal lords need those soldiers as well and since they pay for the soldiers, they got more right to it. The king probably didn't need the army for much longer, so it was a sensible arangement. Except when the king did need them longer.

And your example is flawed, because at the time of Agincourt England had replaced this feudal idea with a system of cash-payments. England needed to fight an oversea war, so the forty days limit (and this includes the time needed to get to the assembly point) was a severe problem. So, during the thirteenth and fourteenth centuries, instead of sending men you could pay the king a sum of money (originally, you would have to pay a fine if you didn't show up). For this money, the king recruited soldiers and mercenaries, which he paid from his own pocket. This allowed him to keep an army in the field for as long as he wished, or as long as his money lasted. Also, it made his armies loyal to him alone, and not to their feudal lords.