He loaded them onto ships and dumped them off in southern Mexico and I believe he deported 2 million.
Even more must have left on their own.
I decided to Google “President Eisenhower deportation of illegal immigrants”. Below is a Wiki article. A key point is that Mexico ASKED US to send them back and cooperated fully with the program. This is unlikely to be the case this time. THe number deported was slightly more than 1 million.
https://en.wikipedia.org/wiki/Operation_Wetback