Need help with military units for my novel . [ OT ]

Well if it's for a novel there are a few ways I could see you going about this. 
 
 1 ) Preplanning an entire structure with a history, lots of research and a lot of detail. This would be if the level of detail and realism was the part meant to be enjoyed, such as if creating your own consistent language. This would appeal to some people but is a lot of work, you really just need to know your stuff. 
 
 2 ) Go with something simple that fits the plot. Want battle background noise while a more personal drama goes on in it? Two big armies, their units are vague until important ( We do n't know there's archers until just before our heroes have to deal with arrows, by the time we see the dragon swoop over the mountain it's ready to shoot fire. ) You can throw in foreshadowing but you do n't want an information dump. You want to portray the battle as big and confusing but still focus on the characters to make it seem as if the rest of the battle is as interesting as what they are doing. 
 
 3 ) The final one is a military drama. This is similar to the 2nd one but it would n't make sense for a military book to be so vague about the military. The way I would deal with this is make sure all of the characters have got a very clearly defined role to preform, and that their personalities are more interesting than their role. 
 
 Hope this helps, but you might have been looking for something completely different, or my advice is n't up to scratch. 
 
 Good Luck with the book
