Wry and cranky, droll and cantankerous — that’s the Mark Twain we think we know, thanks to reading “Huck Finn” and “Tom Sawyer” in high school. But in his unexpurgated autobiography, whose first volume is about to be published a century after his death, a very different Twain emerges, more pointedly political and willing to play the role of the angry prophet.

Whether anguishing over American military interventions abroad or delivering jabs at Wall Street tycoons, this Twain is strikingly contemporary. Though the autobiography also contains its share of homespun tales, some of its observations about American life are so acerbic — at one point Twain refers to American soldiers as “uniformed assassins” — that his heirs and editors, as well as the writer himself, feared they would damage his reputation if not withheld.