Answer: They fought because if they didn't, they would just be back in slavery. At the time they were in slavery. They gave them an offer to fight and not work.
Explanation:
Uh... China? Just a wild guess :)
That is because theories of environmental determinism often led to racism and eugenics because it was believed that psychology and physiology of people varied due to their location, which meant that other races were different from us, and it was mostly used as an excuse to treat them as inferior.
