Never played as Brazil, but man does it seem they can field a large army! I tend to like playing the not-huge nations, so I'll probably give them a go at some point as well. :)
Even with ~100 divisions working together, I can’t seem to defeat any of Peru’s divisions.
I notice you are down to zero manpower. My guess is your units are under strength and are therefore combat ineffective. You either need more conscription or you need to delete some of your units so the manpower is absorbed into the others.