I've read several biographies that pertained to military history in England and France especially around the time of Napoleon. I noticed that the authors referenced the ruler requesting the service of generals. How did that system work? Were generals able to refuse orders? How was that structure managed?
Until at least the time of Louis XIV and "absolute rule," the French kings, operating under the feudal system, consulted with, and "asked" the nobles regarding the taking of action. Basically, the king was considered by the nobles, "the first among equals."
At the battle of Crecy, for instance, the nobles called for, and got a late afternoon attack after a long day's march, even though King Philip VI preferred to wait until the following morning.Generals tended not to disobey orders "individually," but if "most" of them were of the same opinion, the king would usually relent. Put another way, generals and nobles would obey the king's "orders" if it seemed like he was speaking for their "peers" but they collectively wouldn't obey the king if it seemed like he was speaking only for himself.
The later, "absolute" rulers in France didn't fare so well. Kings Louis XIV and XV managed to rule "absolutely" without support of the nobles, but their descendant, Louis XVI paid the price at the guillotine. So did Robespierre, who tried to rule "absolutely." Napoleon, who started off as the first of equals exercised "some" restraint, later on.
The answer to "elsewhere," specifically England, lies with the Magna Carta. That was another situation where the nobles banded together to limit the power of the king below their own, "collective" power.