Earlier quoted context omitted.
Nature. What better secret ally to start a war with?
Cows. No one suspects something so docile and they outweigh us as a species by about 50%. We bred them to be tasty, but they were the ones using us.
"We bred them to be tasty, but humanity's reign over nature crumbled when they learned to taste"
"We bred them to be tasty, but no one could foresee that it was us that would be devoured"