During Salvador Allende's presidency, Marxist Edward Boorstein was an assistant & close friend of Jaime Barrios, an economic advisor to Allende. Boorstein's Allende's Chile: An Inside View is the author's report on what happened, what Allende achieved, & why he failed.
I knew nothing of this history & found the book well worth the read.
Boorstein's proposition is that Allende failed because he behaved honorably, while everyone else – Chilean political parties, Chilean armed forces, Chilean press, international corporations with Chilean interests, United States government (Nixon, Kissinger) & CIA – behaved dishonorably wherever dishonor served them well.