J. Sakai’s book “Settlers” talks about that most excellently.

Another relief valve for those tensions would be importing vast scores of European Immigrants to take up just enough of the backbone labor position to crush any kind of worker revolt, while you further genocide and deport the current backbone of your labor force; Mexicano, Chinese, Japanese, Native, Afrikan, etc.

I’m still reading the book, but where I’m at now discusses how the main purpose of the New Deal was to resolve the contradiction that is inevitable when you do that. The solution was to Americanize the migrant European labor force. Hence the creation of the Middle Class if I’m understanding it right.

The middle class being, a strata of Labor paid just enough out of the spoils of imperial conquest to keep the bulk of Labor from wanting to rock the boat too much. Strikes and other various labor disputes were deemed okay if they were directed internally at getting a bigger share of the loot, and not at overthrowing US imperialism or something similar.

So while during The New Deal the Army wasn’t used as it was historically to break up strikes on behalf of the capitalists, the army was used quite extensively to shut down revolutionary revolt in Puerto Rico.