some people did not know why they were kicked out. A few were told and it boils down to them being labeled a security risk. They need t o serve in the military to become full citizens, so this is barring them from that right in this "land of the free". There is even a possibility of sending them back to their country of origin, for no reason other than than whatever brand of "its not racism: you prefer.
https://www.nytimes.com/2018/07/05/us/charlottesville-plea-hate-crimes.html
Take a look at this, a fascist plead not guilty to hate crimes involving driving a car into a bunch of anti-fascist protesters, who arrived in response to a white nationalist rally. He is a racist, white nationalist, and is anti-semitic. Let me guess, for the hundredth time this year this fascist terrorist attack was just a result of mental illness (a card only played when the person is a white right-winger)
I remember the Roman times, oh how lazy they were with their plots of land. But oh how many unintegrated tribes would swell up the auxilliaries and make the Roman military undefeatable in numbers, tactics and the knowledge their auxilliaries presented.