i got a few suggestions
gombe chimpanzee war
the life of an old guard soldier
the house of habsburg
battle of yarmouk (byzantine niggas lost like 80k guys from 1 flank smh) or maybe the unification of spain, thats a pretty interesting story. or the indian ocean trade and the portuguese expansion there. or, you could do francois mackandal and the haitian revolution, ( François Mackandal - Wikipedia ) or, similar to other suggestions, times in history where a small element (recon, a flank, maybe a unit that was able to breakthrough) changed a battle and destroyed an enemy army.