Anything with cavalry pre-gunpowder was really one big game of chicken.
I know that at Waterloo, the Scots Greys advanced more at a trot than full charge.
Not everyone has been around a horse to realize just how large and powerful (and fickle) animals they are. Even fewer have seen a few, let alone one, horse charge at them.
You are pressed to find a soul alive today that can testify to the experience of several hundred horses charging at your direction and you know they intend to charge past, over, and through you. The realization is alone enough to shake your will.
But then there is the sound. Imagine the space in your mind that 5 horses take up, then expand that to get close to what a charge might be sized at. 10 horses isn't enough. not 50 horses. 200 horses? That is not enough either. Imagine 1,000 horses coming your way with 4,000 steel hooves thundering, and you know nothing can change their minds heading your way - and the one thing that is expected to stop them are your and your friend's bodies.
This is a gap in recorded/presented/easy-to-imagine history in which you can imagine the shape of a role of the “Irish” Hobelar as a fighting unit.
Hobelars were mounted on small gaited native pony-horses called hobbies; carrying no gear and wearing no armour and riding practically bareback, a feat made possible by the fast smooth pace of the hobby (whose gait would presumably resemble the Icelandic pony’s tölt or the Mongolian war pony’s joroo.) the Irish Hobby is now extinct, but the name is where we get the word “hobby” from - an activity done for pleasure. This sounds made-up, doesn’t it? You can read a long post by myself and contributors here, which includes this poem from someone describing their fighting style and how annoying it was:
And one amang, an lyrysch man, Uppone his hoby swyftly ran; Hyt was a sportfulle sygthe, How hys darttes he did schak ; And when him lyst to leve or tak, They had fulle gret dispite.
There are a few reasons why you haven’t heard of hobelars (god forbid people have hobbies). It is important to the imperial construction of the myths of the British Isles (and the French) that Celtic people be negligible and subjugated in any narrative of medieval warfare. They did not correspond to a social class outside of warfare: you can spin so MANY sexy aristocracy-reinforcing tales of chivalry around knights that we’re still doing so today. Sexy tormented superhero with his ARMOUR and his SWORD and his big HORSE - let’s roleplay this 5 million times, and for political comfort, rather than trampling the peasants he now rules, we shall enshrine and repeat the safe metaphorical image of the “dragon” for him to fight as well…
Guy Who Just Caught A Wild Hobby From A Bog And Doesn’t Wear Armour (and runs around bareback, throwing stuff and being incredibly fast and annoying, and vanishing when you tried to kill them back) is just… less sexy. They literally weren’t superheroes. There is discomfort as well - if we kept their imagery, we couldn’t give them fictions to fight; hobelars were not romantic, they had no fixed honour; they were always a scrambling skirmishing fighting unit for killing people. As an academic puts it:
The hobelar is very much the poor relation in the study of the English armies of the fourteenth century, eclipsed by both the man-at-arms and the archer. Our understanding of his origins and role has been wholly based on only two major studies of this troop type: J. E. Morris’ ‘Mounted Infantry Warfare’ in 1914 and J. Lydon's ‘The Hobelar: An Irish Contribution to Medieval Warfare’ in 1954. The lack of interest might be considered surprising, given that Morris saw him as the precursor to the mounted longbowman, while Lydon called him ‘the most effective fighting man of the age’, referring to the hobelar as ‘an entirely different type of mounted soldier’. Yet other historians have been happy to accept the conclusions of Morris and Lydon, considering the hobelar only in passing. Perhaps the reason that so little work has been done on him is that he is always considered in comparison to the man-at-arms – the elite warrior, in his shining harness, doyen of chivalry and a core element of the medieval political and social elite – and the longbowman – the almost super-heroic, Hundred Years’ War-winning, nationalistic symbol of medieval English, and Welsh, martial prowess. By contrast, there is little if any mention of the hobelar in the battle narratives of the middle ages; they have no great role to play in the successes of the English over the French. They do not form a political and social class within medieval society and there is no way, therefore, to discuss their impact outside of the military sphere. It is also almost certain that their Irish origins have counted against them too. Medieval Ireland has been considered militarily backwards by most historians of warfare, who seem to have inherited something of the dismissive tone of their English sources…
Right. 
You’ve read the posts above. You have dutifully pictured the mental image of being a pikeman, Just Some Guy with a big pointy stick, while thousands of pounds of steel-armoured horseflesh ridden by braying Tories comes at you. You have understood that this is inherently alarming, even if you understand the military theories involved, and are prepared to make horse-kebabs.
Now picture being that pikeman when hobelars turn up. First off, the hobbies are WEIRD. They’re fast and tiny, and they move Wrong:
Rather than lining up to be kebabs, as you expect, they feint - dance up to you like weirdos and turn away. They show off how - unencumbered and in good control of their hobbies - they can pretend to do the scary charge thing, breaking your will, but not get kebabed. They are not wearing armour; they’re not using saddles or stirrups, but some of them appear to be archers (?!) sometimes the hobelars get off and wind you up a bit and then jump back on their stupid hobbies. Psychologically they seem more like YOU, but then there’s the horses. They throw spears, or arrow-spears called “darts.” They laugh at you. They have amazing control of their hobbies, who turn away from pikeheads on a dime. The sight of hobbies skirmishing was described (above) as “a sportful sight” - presumably if they weren’t doing it at you, when it would be SO annoying.
There is zero expectation that Celtic mounted skirmishers will break a wall of pikemen. The hobelars have been sent to annoy you. What if this is part of their function, a natural activity in their wheelhouse, and they have perfected it. What if it’s working. What if, by the time the big shiny horses with their big shiny nobles come, you’re already a bit shaken…
Not saying this scene ever happened in history, but you can see from this a bit of how these histories are constructed: here is a unit that was effective and influential in its time and gave its name to “hobbies.” Here are the places where it would seem logical to use them. We have lost much of what would have been known about how they fought at all. The primary source for the quote of the “iyrysch man upon his hoby” is preserved in one single corrupted document in a corner of the internet that took me a morning to find. We will never forget knights, but with a strategically placed EMP, we would probably lose our ability to remember and connect over hobelars (why would anyone care.)
but care when you find yourself thinking that the entire system is pikeman vs knight, one vs the other, an armchair system that plays out like an RPG, rock-paper-scissors: care because so much of history is a spectrum of forgotten people.
oh... That's why the toy is called a hobby horse. I ... Thought the name came from "hobby" like a thing you do for fun.
The other way around! The toy “hobbyhorse”, a toy horse that gives you pleasure and lets you play pretend but clearly isn’t a real horse, gave its name to “hobby,” “activity for pleasure.”
The etymology of “hobby, a thing you do for fun” comes directly from “hobby, a little horse”. Which was once a real sort of little horse. Isn’t that great! We all need more hobbies.
