I've never quite been able to find the answer to this, usually search results come up with something about the old units of measurement and the like, so I'm turning to the pros.
During Medieval times, how exactly were units organized and how large were units? Was there some kind of standard organization of 'this many troops form this size of group' like how modern militaries have determined, or was it more of an on-the-spot, whatever is most useful kind of thing? The only exposure I have to any notion of the organization or numbers of troops for a unit is from a strategy game I play, which while being a lot more accurate than the average game or movie in its depiction of warfare, is not something I want to use as a reliable source. In case it is or just to have something to reference what I'm asking about, generally units are grouped into one type of role (eg, pikemen, spearmen, heavy infantry/dismounted knights, cavalry), and form, for lack of a more accurate term, regiments of troops that are fairly organized and usually distinctly hold square or rectangle formations several men deep and as much as ten to twenty men wide. Infantry is usually grouped as 75-150 men, Cavalry is grouped at 40-70, and General units (the general and a protecting cavalry unit) at 20-40 troops.
I know its better to narrow down the scope of the question, so for the sake of it, let's assume we're referring to the general era where professional and standing armies began to be more commonplace as opposed to conscripts and levies. Additionally, if the question is a bit vague or confusing, I can definitely try to explain it better, this has been burning the back of my brain for awhile now.
Dude, I'm sure people here are familiar with Medieval 2 Total War (it comes up quite a lot as a starting point for peoples curiosity). For other people answering who are unfamiliar, the game period is roughly mid/late 11th to mid 15th century warfare, in Europe, North Africa and the middle East.
I've never quite been able to find the answer to this, usually search results come up with something about the old units of measurement and the like, so I'm turning to the pros.
The reason there is no "simple answer" is because this requires a very long answer and I highly recommend that you do some reading of material to get an overview. You are asking about the Early Modern military revolution, which is a huge subject matter. You are correct that there was a major shift in how wars were fought, so even within the period of 1470-1570 there was a massive shift not only in how wars were fought, but also how states were run. And yet more shifts in the 1600s.
You can start here and here to at least get a sense of what was truly happening, and why asking, "Between the Hundred Years' War and the Renaissance" requires a very big and long answer.
As far as the organization goes, even if we just look at the period of the Thirty Years' War, this evolved greatly, for reasons that are still debated today. You can read this to get an idea of what it took to raise men for fighting.
The Spanish preferred commission at least until the last third of that conflict. Most others had to rely on contracts. Over time it became harder to find men, so units became smaller and there were ever higher ratios of officers to soldiers.
Please consider reading through:
When and where are we taking about?
Europe is kind of a large place, and the Middle Ages covers a thousand years.