The right-wing elites were confident they could use him to their advantage. Yes, Adolf Hitler was ridiculous and vulgar, a tin-pot demagogue instead of a smooth politician, but he knew how to excite the nationalist base and deliver a whopper of a speech. Germany’s conservative politicians assured one another that they would still be the ones to pull the puppet strings. As one of them put it, “In two months, we’ll have pushed Hitler so far into a corner that he’ll squeal.”

Needless to say, the adults in the room overestimated their own powers of containment. In “Hitler’s First Hundred Days,” the historian Peter Fritzsche shows how Hitler and the National Socialists wasted little time after he was appointed chancellor on Jan. 30, 1933, in crushing what remained of the Weimar Republic and installing “the 20th century’s most popular dictatorship.”

The changes were audacious, and they were swift. On Day 4, Hitler and his conservative allies censored any press that showed “contempt” for government. On Day 7, he established links between his brownshirt paramilitaries and the official law-and-order apparatus of the state. The Reichstag fire on Day 29 gave Hitler the pretext he needed to get President Paul von Hindenburg to sign an emergency decree suspending civil liberties, and the Reichstag elections a week later consolidated the Nazis’ grip on power. On Day 61, the Nazis organized a nationwide boycott of Jewish businesses, and six days later purged the civil service of Jews.

“A quarter past 11 led, in only 100 days, to the Thousand Year Reich,” Fritzsche writes, referring to the hour before midnight when Hitler and the conservative elites made their back-room deal to appoint him chancellor.

Fritzsche describes an era that has been covered by other books — not least his own — many times over. As an esteemed historian of how ordinary Germans accommodated themselves to the Nazi regime, Fritzsche is neither revising his scholarship nor breaking new ground here. But there’s something particularly clarifying about the hundred-days framing, especially as it’s presented in this elegant and sobering book, which shows how an unimaginable political transformation can happen astonishingly quickly. Fritzsche quotes the newspaper clippings, diary entries and correspondence of the time to give a sense of what everyday life was like in Germany during the spring of 1933, when the political impasse of Weimar’s divided democracy gave way to decisive, state-sanctioned brutality.