The small problem is that a (Western European) medieval army was an ephemeral structure. Rarely did a medieval army exist for more than three or four months. I don't understand how you can establish a meritocracy in such a short time. Not to mention that the greatest achivement of a commander was to keep the men fed for the duration of the campaign.

@AlexP this is true, and it's not an easy thing to overcome. Heck, in Medieval Europe the primary concern of any semibenevolent leader was keeping people fed each year. I'm making the assumption that Lord Gary's domain has enough resources to rise above subsistence agriculture and can rise to a level where a lot of division of labor is possible. Food security becomes part of the supply chain.

There were cases of people being ennobled for exceptional military service, so the concept of meritocracy did in fact exist.

I think almost none of the points was new for the peers of Lord Gary - Logistics, not exhausting your troop, Preserving Food and promoting able Soldiers were all common knowledge to generals since Roman times. - Lord Gary would not really get an edge from this already available knowledge.

@vsz It's not that people weren't promoted for being good at their jobs - the problem is that some of those promotions were hereditary. To get a meritocracy, you would need to be able to also remove the hereditary privilege, which was serious business that was liable to make the lord (of the lord) very unpopular among his vassals, subjects and peers alike.

About training — while you can make your people have mandatory training (like in hundred-year-war England, when yeomen were required to train with a bow weekly), you can't make them train too much, because you need them to work in the field. Also, for that reason you would hardly get any "volunteer or drafted" soldiers to "train daily", if they training, they're not plowing the field and not bringing food to the granary, while consuming food and requiring money for arms.

@Luaan : I doubt modern social structures would have worked well given the economic, social, and technological aspects of that time. Few people had the means to pursue whatever they wanted and get the education they wanted, but the heirs of noble houses did at least receive education in the skills they needed the most. And it provided stability. Take a look at how there were both hereditary and elective monarchies, and over time there were more and more hereditary, and less elective monarchies, as the election of the new monarch often caused strife, instability and sometimes even civil war.

"For some reason, the nobles kept equating bloodline with skill in battle." I think it's more that they fear an army not run by nobles might be tempted to take over.

It is hard to say if Lord Gary's plan to use meritocracy would really help. It wasn't a totally unknown idea. Presumably some other extenuating circumstances prevented it from becoming widespread. Presumably if Lord Gary is working in some sort of feudal system, his lower lords aren't going to be too happy if, upon receiving their levies, he says "Thanks for the dudes, you can go home, I'm going to let some of my peasants lead them and take the glory." I mean, maybe he could restructure his whole society to make this work, but that falls outside the clearly defined scope.

@user28434 What I was referring to was the larger potential pool be training on a weekly or monthly basis. Allowances could be made for the planting and harvesting seasons. Daily training is not required of the larger population. It's only the active military that trains daily. That way fields get plowed and the harvest goes without a hitch. This would be similar to the Hundred Year War requirement on english yeomen.

@vsz The concept of Meritocracy can be blended in with a feudal system with a strong enough or ruthless enough monarch. Local lords supply the levy and will go off to war in a leadership kind of position but you take away the starting rank. Your earl and your duke starts as a young man in campaigns as the equivalent to a 2nd lieutenant and only advances if he is effective. likewise your baronet and marquise. Add the proviso that if he is not effective, he will be dismissed and not invited back to play warrior in future campaigns.

It is all limited by the economy. But Lord Gary can start by using his skills to improve that first. As useful information is for warfare, it is even more useful for trade, so Lord Gary can start by offering services of his messengers and other communication methods to his merchants, basically setting up a post service. Better information would make the economy run more smoothly and that would give him edge in being able to supply his army better than his opponents.

Also true. In this I have had to assume a kind of economic baseline where division of labor can happen beyond the level of straight up survival. And yes, the traders and merchants would be absolutely critical for information gathering and transmission methods. Maybe he could give them incentives to spend some time developing better methods for communication over distances.

@PaulTIKI, feudal system or strong monarch — choose one, you can't have both.

"At home, just about everyone who can hold a spear should train with them periodically. Make it a universal requirement" - and just for completeness; what does Lord Gary do to ensure these now well armed peasants don't decide they want a new leader the next time there's a poor harvest?

@Bilkokuya, he treats them well and fairly. That would be step one. Step 2 is to keep the steel weapons under lock and key when not being used for training. One does not need to be an absolute tyrant to keep the rabble in line.

@user28434 that does not make any sense. Why would a strong monarchy and a feudal system be mutually exclusive?

@PaulTIKI, because feudal system appeared not because people thought feudal hierarchy is pretty swell, but because the monarchs couldn't project their power all over their realm. They were weak in that regard. And they had to give away parts of the realm as fiefs to people they were called vassals in exchange of support. And in their fiefs vassals had more power in their realm than their liege, and they quite liked it the way it was. So, it monarch will become "strong" and starts micromanaging armies, vassal levies to be specific, they would naturally object and try to put the monarch down.

@PaulTIKI, CONT'D: And it will mean internal war between vassals and their liege(now considered tyrant). Either vassals will win and feudalism keeps being, or the monarch wins and absolutism starts (like it happened in RL in the late Late Middle Ages - Renaissance and forward).

@PaulTIKI, for example when vassals won, completely dominated their monarch, and kept feudalism past the time everyone moved on you can look at Rzeczpospolita and their Golden Liberty.

+1 for Jubei the Arrow. Brandon Sanderson has said that a certain scene from Oathbreaker (you'll know which one if you've read it) was based on that story.