Very interesting article. I’d like to add a couple of of notes, if I may.
We don’t really have evidence for mass call-ups in western Europe after about 1000 AD; the levy persisted in England in a limited form until the end of the 13th century, but went extinct in France much earlier. Yet, true professional, standing armies don’t appear until the tail end of the 15th century.
In the meantime, warfare mostly seems to have been the province of semi-professionals. Short of an emergency defensive situation, Joe Serf likely wasn’t going to war; he was an impediment and you didn’t need or want him. But you did have non-aristocrats with military skills and equipment — both probably passed down through military families; by the 14th century, when the records are there, you see the same names showing up again and again — who went to war on occasion. Mercenaries — that is, private soldiers hiring out as a body — appeared in large numbers in the 12th century, but even before that, there were soldiers serving for pay, either as part of the households of lords and kings or on a temporary basis i.e. for the duration of a campaign.
Even the English levy by the 13th century had become much less a levy than a calling up of a given number of fighting men. Companies (usually archers) were raised as-needed from the shires by the local royal officials and forwarded to the king. The commanders of these companies show up again and again, sometimes leading companies, sometimes fighting as individual volunteers.
For the most part, very large armies were not needed because, as you note, medieval warfare largely revolved around raiding. I will go further and state that medieval warfare was fundamentally different in nature from either classical or modern warfare. It was positional and Vegetian, rather than Clausewitzian: that is to say, the goal was to seize and control territory, not to bring about the total destruction of the enemy’s will and capacity to fight. Armies were valuable and difficult to replace, and medieval generals hazarded them in pitched battles as seldom as once a generation; Henry II fought none, and Richard I, his son, fought only two, both while on Crusade. As an attacker, this meant that you would try to weaken the enemy’s strategic position by raiding, which had the added advantage of sustaining your army, preparatory to besieging and capturing the weakened fortified points that would enable you to lock down your control over that territory. As a defender, you wanted to shadow the attacking force with a near-equivalent force so as to prevent it from dispersing to forage. If the enemy army can’t forage, they have two options: retreat, or try to force a pitched battle. This is what happened at Hastings in 1066; William did not, in all likelihood, want to fight, but the close presence of Harold’s army made it necessary.
For reference, I would see the essays in John France’s Mercenaries and Paid Men: The Mercenary Identity in the Middle Ages, Matthew Strickland’s Anglo-Norman Warfare (especially Gillingham’s two essays), and David Bachrach’s Edward I’s Centurions: Professional Soldiers in an Era of Militia Armies.