I've been greatly confused as of late in regards to Medieval armies and their composition. On one hand, some sources seem to imply that armies were mostly nobles, with them gradually being replaced by middle class servicemen later into the 13th and 14th centuries. In other sources, they seem to imply that a lord would go out and recruit soldiers from the population or call some kind of muster.
Which is more accurate? I must admit I am only really familiar with Early Medieval warfare, but the makeup of armies changed drastically over the course of the Middle Ages. Were the armies comprised of mostly nobles, or was it paid "professional" soldiery? I was always taught the former, but it seems that there is a lot of conflicting information on the subject.
To narrow the topic down further (since that is quite a lot of time outlined above), just try to take a vertical slice of the most average medieval system. I am also aware that different kingdoms used different models depending on what cultures they were exposed to (England and France adopted more Normanesque models while Italy, Germany, and Spain started with more Roman models and seemed to gradually move more towards nobility, which was a Migration Period Germanic system of landed warrior classes, at least that's how it appears to me)
On one hand, some sources seem to imply that armies were mostly nobles, with them gradually being replaced by middle class servicemen later into the 13th and 14th centuries. In other sources, they seem to imply that a lord would go out and recruit soldiers from the population or call some kind of muster.
Both are actually true, you just overlooked a detail: nobles served primarily as shock cavalry or super heavy infantry. In those roles, they were being phased out by the servicemen, but the rest of the army was never noble in the first place - for starters, that would be one small army.
The non-noble part of the army was recruited from population or filled by mercenaries (there's little practical difference between the two at this point), and we don't know a huge amount about it, since the chronicles tend to talk about the deeds of the elite. When a source says that five lances were contributed by someone into the armed force, he can mean three things: individual heavy cavalryman (usually not the case), heavy cavalryman with squires to carry spare lances and shields and act as medium or light cavalry, or a knight with retinue, including foot soldiers.
You may find this post I made on Anglo-Norman army structure useful.