5 Feet of Fury

Left wing violence against blacks has a long, sordid history

Yep:

In response to this unwelcome competition, AFL chief Samuel Gompers thundered: “If the colored man continues to lend himself to the work of tearing down what the white man has built up, a race hatred worse than any ever known before will result. Caucasian civilization will serve notice that its uplifting process is not to be interfered with in any such way.”