I was first introduced to this by an old SPI boardgame whose name escapes me at the moment. What struck me at the time was how I would do the "proper" boardgame tactic and mass enough forces to wipe out the enemy, only to have that blasted counter fall back instead. I was used to the D-Elim combat results, and it took a little reading to remember that units were not normally wiped out in the course of a fight. Oh, granted, in WW2 there were armored units that ended up with no tanks functioning at the end of a fight, but there were other assets in the division/brigade/combat command/kampfgruppe.
A few months later I saw one of the best microarmor games ever. There was a crossroad with only one or two buildings, not enough to be much of a strongpoint. But right nearby was a large wooded hill. The enemy had an observation post up there, and no tank was going to go wandering through the trees. This was a job for the infantry (much despised by a lot of treadheads). In they went. Artillery fired in support, but two turns after it was requested. And that meant that it wasn't always accurate, had to be adjusted, and so on. Both sides got stuck in, reinforcements were sent in, and quite a lively battle developed. I don't recall who won. I do know that everyone appeared to have a good time, and all of the fearsome armor on both sides sat around doing very little.
I watched that, and wondered why nobody tried to outflank the position. A week later (we were gaming every weekend at a local hobby shop) I saw someone stare at a position, and decide to turn it. We ended up with a map game for a bit, and then got stuck in as a small force (mine) fought a delaying action while reinforcements marched to the scene. This was very much what nobody had expected. And it was a lot of fun.
This wasn't always likely in the 18th Century, especially the earlier part. Armies (and generals) were still in the unitary mode. This meant that you concentrated everything on the field of battle, being as strong as you could at the point of contact. The Duke of Marlbofough tried something different on the battlefield that 100 years later became Waterloo, having his brother with 20 battalions hidden behind the enemy position, but the Dutch Deputy on Mission, Slangenburg, couldn't see it and managed to hold things up enough that the battle was not fought. Marlbofough didn't try that again. Well, okay, Overkirk at Oudenaarde, but not after that.
Part of the problem was communications. Part of it was administrative, and part was social. After a bit you didn't say no to the CiC, even if you didn't agree with him. Marlborough managed to overawe his subordinates enough. Frederick tried managing separate forces at Torgau, and showed how all of the problems you had when someone didn't keep to the timetable. The Austrians in the Seven Years War were pretty good at the different columns concept, but Maria Theresa would remove the generals who caused problems. And de Saxe, in the War of the Austrian Succession managed to make it work, but by then he was a Marshal-General, and only the King and Dauphin outranked him. Even the most pig-headed member of the French nobility had to take orders from that "Lutheran bastard".
Now part of it was also doctrine. As I said, these were unitary armies. The detached columns were the province of only the top generals. It wasn't "normal", and it took both the invention of the division (pioneered in 1745 by de Saxe) and a few books on mountain warfare before the idea began to work its way through the officer corps. But you needed a common doctrine, staff as well as otherwise, and that didn't happen very often. The Austrian staff advances in the Seven Years War deteriorated afterwards because it wasn't encoded and become part of the regulations. The French finally achieved it in the 1790s, and others copied it. It brought a flexibility to warfare that made things a lot more fluid.
So how do we imitate this on the tabletop? Well, we don't, not directly. I know of one attempt right now, sort of a "narrative" campaign. You issue orders ("Brigade A to move from Point A to Point B"), and the GM carries them out. Will it work? Perhaps. I hope so, but it depends upon the GM.
For our miniatures campaign, there is nothing to stop players from using detached forces to achieve campaign objectives. But be warned, small forces can suddenly confront the enemy main army and get crushed. I've fought tabletop battles where I was outnumbered 3:1, and it is no fun. I escaped, but that was more due to the enemy not talking with each other.
So look for fights where one side is outnumbered, and not by a little bit. Expect some huge disparities. But also realize that while one side can be outnumbered at Point A, that means they probably outnumber the other side at Point B. Tit for tat. That is one of the reasons we fight miniatures campaigns. It sure isn't to generate "even" fights. (insert rant about "even" fights here).