In my novel, there is a large scale battle involving several factions, tens of thousands of fighters, and is a defining part of the book, as it lasts for a good deal of the novel. As I wrote it, I tried to paint a clear picture for readers, but I found it difficult to decide how. How in depth should it be described (General descriptions such as simply stating that many fighters died, or describing in depth the specific experiences of the fighters and leaders)? Is there anything specific that should be avoided that could bore readers? If this question is to broad, I will edit it.
I agree with Lauren Ipsum, byt read from a variety of authors, not just one. In addition, read The Art of war. I know I just gave you more homework, but if you know what each side's strategies are, you could establish that for the reader, then twist things up.
I'd also recommend reading the Illiad (or at least the battle scenes). Homer does what you do--says that this dude got stabbed through with a spear, and then "the darkness" fell over his eyes.
In any rate, try to have emotions. In the sense that you could zoom in on a few soldiers and their emotional connections with each other. Soldier A is friends with soldier B. Soldier B hates soldier C, so they both try to kill more enemies than soldier C, and they're having a grand time until Soldier A dies, and then soldier B is enraged and starts killing off everyone.
If you take the time to include little vignettes such as these, the fighting will seem more personal/visceral, since it's not just two random armies going at each other, but people fighting people.
Think of the battle of Helm's Deep in the Two Towers--Legolas and Gimli have a contest to see who could kill more orcs--this provides comic relief, and humanizes their army. Aragorn fights to avenge a dead friend--this further humanizes their army.
Humanizing both sides would be harder. Think how much longer LOTR would have been if Tolkien had introduced a bunch of sympathetic Orc characters who were hunting for the ring--not to mention how this would muddle the narrative. If all of you MC's are on one side, focus on the specific experiences of their side.
So in conclusion, focus on specific experiences--it makes the battle more real, and is more engaging to the reader overall. I hope this helped.
I recommend that you look into military theory and historical examples. The subject is larger than life, so well chosen indeed.
- The Art of War by Sun Tzu
The Project Gutenberg version with commentaries included. May sound outdated but it is still being studied today.
Some few battle pundits shaming the biggest army the world then knew.
- Gaius Julius Caesar's Commentaries on the Gallic War
A whole series of battles and the biggest personal marketing campaign of the time.
This battle could have gone two ways until the French elite Imperial Guard faltered in heavy crossfire, and broke Napoleon's career.
- Charge of the Light Brigade
Just one unwise tactical move but still a great example of an epic battle scene.
Pretty random list. There is a whole lot more to discover if you are so inclined.