Megamorphs #3 dealt a lot with the past human wars by placing the Animorphs in them, so I think you might enjoy that. There's also #19, 21, 29, 30, 31, 38, 49, 50 which were also some of my favourites because of how much more mature they were for a kids series. They reflected more on the type of war the Animorphs were stuck in and the difficult decisions they had to deal with, whether it was for the world, or for the people personally affected by the lives that they lived.
#46 especially (part of the final arc of #45-54) dealt with the Yeerks manipulating the humans to start their own world war to weaken them as a race to take over, and #47 paralleled the fight for the free Hork-Bajir Colony with the Civil War of Jake's Great Grand Father, so those might be of a interest to you as well.