and the civil war and World War 2:
Zinn points out that war is the indiscriminate killing of huge numbers (often thousands and thousands, millions sometimes) of people for uncertain ends. Maiming of thousands and sometimes millions more.
War is a top-down exercise; it cannot be carried on by any group in society but those who have their hands on great wealth, law and courts, power. And so when the war is done very little reform the average person wants is achieved. After the Revolutionary war, very wealthy people made the constitution about property. After the civil war slavery was turned into state terror and semi-slavery for black people. Did World War Two end fascism? Not at all; turns out fascism lay low for a bit, and then emerged strengthened.
Inbetween war and passivity there are a thousands possibilities of what we could do about something.