If It Had Happened Otherwise is a 1931 collection of essays edited by J. C. Squire and published by Longmans, Green. Each essay in the collection could be considered alternate history or counterfactual history, a few written by leading historians of the period and one by Winston Churchill.

Alternate history is a subgenre of speculative fiction in which one or more historical events have occurred but are resolved differently than in actual history. As conjecture based upon historical fact, alternate history stories propose What if? scenarios about crucial events in human history, and present outcomes very different from the historical record. Some alternate histories are considered a subgenre of science fiction, or historical fiction.