In this version of history, Giuseppe Zangara—who in reality killed Chicago mayor Anton Cermak in 1933—assassinated Pres. Franklin Roosevelt instead. Without FDR’s leadership, America delayed entering World War II....
Hmm I had not read this book... but sounds to be the inspiration jump off point for the famous Star Trek “The City on the Edge of Forever” episode
That twist is a bit of a laugher. FDR was a crappy president in almost every measurable way.