One of my favorite historians was Howard Zinn, author of A People's History of the United States.
A People's History was first published in 1980 with little-to-no promotion, and a first run of only 5,000 copies. Somehow, mostly through word of mouth, it became the people's bestseller, achieving sales of one million in 2003.
Howard Zinn was definitely on the far outside edges of unapologetic liberalism. He told stories of suffragettes, union organizers and war resisters. Instead of exalting Christopher Columbus he accused him of genocide. He dissected presidents from Andrew Jackson to FDR.
My favorite Howard Zinn quote:
What does it take to bring a turnaround in social consciousness - from being a racist to being in favor of racial equality, from being in favor of Bush's tax program to being against it, from being in favor of the war in Iraq to being against it? We desperately want an answer, because we know that the future of the human race depends on a radical change in social consciousness.
It seems to me that we need not engage in some fancy psychological experiment to learn the answer, but rather to look at ourselves and to talk to our friends. We then see, though it is unsettling, that we were not born critical of existing society. There was a moment in our lives (or a month, or a year) when certain facts appeared before us, startled us, and then caused us to question beliefs that were strongly fixed in our consciousness - embedded there by years of family prejudices, orthodox schooling, imbibing of newspapers, radio, and television.
This would seem to lead to a simple conclusion: that we all have an enormous responsibility to bring to the attention of others information they do not have, which has the potential of causing them to rethink long-held ideas. It is so simple a thought that it is easily overlooked as we search, desperate in the face of war and apparently immovable power in ruthless hands, for some magical formula, some secret strategy to bring peace and justice to the land and to the world.
Howard Zinn, The Progressive, 2005