As an avid consumer of the fantasy genre, whether it be high-fantasy or low-fantasy, I've come to realise that there were many issues regarding the portrayal and/or executions of a majority of battles featured within this genre.
Putting the 'the forces of good and evil scream and then charge blindly into each other' stereotype aside, I just see a concerning amount of battles where details are skimped save for how epic or grand the writer wants the battle to seem. Whether it be something a simple as the weapons and armour of the belligerents to something as complicated as the tactics used and the general flow of the battle, a lot of portrayals of battles I've seen fail in these aspects (and also fail to provide a reasonable explanation why).
Now, I know what some of you may say something along the lines of 'so what? It's just a fictional fantasy, so what if the author skimps out one these details, that won't have any effect on the audience's enjoyment of the battle, right?'. Wrong. That's so wrong.
This may seem like a tangent at first but bare with me.
Generally speaking, in any narrative, a major aspect of the audience's investment into the story is derived from tension, particularly, the rise and fall of tension, how the balance of power swings between the protagonist and antagonist. It is the 'small wins and small losses' that switches the battle between the characters' favour, which works well to draw the audience's investment into the conflict.
Fictional battles are (especially) no different, the audience is drawn into the changes of tension within the battle. A battle can be as a grand and as epic as you want, but without these changes in tension, it's ultimately just a vapid light show that you experience and then promptly forget.
And it's because of my aforementioned details of tactics and such that makes these changes of tension believable for the audience. Although the audience will understand that what they are reading is ultimately a work of fiction, they would be more likely to suspend their disbelief and enjoy the writing of the battle if the author pays attention to the details.
To make my point clear, I'm going to make an example of a show that's been beaten to death since the premier of its final season, Game of Thrones (spoilers if you care.) One of the major events in season 8 of GoT is the infamous 'Battle of Winterfell' between the forces of the living and the army of the dead.
The first change in tension in this battle is the initial charge of the Dothraki (which are highly capable horsemen within the GoT universe) into the army of the dead. This charge is the first 'minor win' within the battle, with thousands of screaming dothraki charging fearlessly into the ranks of the undead, the sky lit by the light of flaming boulders fired from supporting artillery catapults.
Although the audience is would be doubtful on whether or not they would succeed, they would still feel some level of relief because of how the scene portrays the heroics of the dothraki (as well as previous experience the audience has with the dothraki being very effective in previous battles).
This 'minor win' quickly becomes a 'minor loss' as the dothraki crash into the ranks of the undead, their initial success quickly turned around by the sheer numbers and relentlessness of the undead horde. Within seconds, both the dothraki and thus the audience are thrown into despair as the ill-fated charge of the dothraki comes into fruition.
Now, take away the superficial glamour of the scene's portrayal and think critically about the causes of the minor win and the minor loss.
To put it bluntly, it was caused by the forces of the living making a stupid decision. The dothraki are lightly armoured cavalry whose effectiveness on the battlefield is derived from the initial impact of their charge and whose same effectiveness quickly wanes when stuck in prolonged combat in the same spot.
On the other hand, the undead are unfeeling monsters who never tire and easily outnumber the living, making them able to defeat anything by sheer attrition alone. The commanders forces of the living are aware of both of these facts, yet they still went ahead with their decision to send the dothraki to their deaths (who would also then be raised as undead upon their defeat, basically negating any casualties they may have caused during their charge).
And once the audience comes to realise that (which can be both during and after the charge), the emotional impact felt by the changes in tension is nullified.
And that is only the first two changes of tension in the battle, there are many more (most of which fail as well). Also note how none of these details are derived from real-world historical warfare facts but the show's own internal logic.
I know this is an extreme example but it works to illustrate my point. There are also other details within that scene which I omitted but the example is already long enough as it is and these details only serve to prove my point.
To re-iterate my point, it is the details that makes the changes in tension and just the overall flow of the battle believable for the audience and thus, makes it more enjoyable for them.
Moreover, it would be important to note that readers within your audience may be knowledgable in these details and would be more likely to appreciate it when the author takes those details into account (conversely, they will also be more likely to notice the details which the author skimped out on).
So taking all that into consideration, I'm considering starting a another discussion offering help for writing fictional medieval-fantasy warfare so that it doesn't suffer from any of the problems I mentioned. You're free to discuss this with me, this is what the forum is for.
There are a lot of aspects of medieval warfare which I didn't manage to bring up or go in-depth into which I regret but would gladly go more in-depth into if anyone asks.