Point of Divergence

Point of Divergence or POD, in alternate history fiction, is the moment when the fictional world stops following the same timeline as our timeline.

Many alternate history stories use an important battle as a Point of Divergence. In How Few Remain, an alternate history novel by Harry Turtledove, the POD is when important orders that the Confederacy lost are immediately recovered, whereas in our timeline, they were discovered by Union forces. Before this moment the history of How Few Remain is the same as ours, but from this moment onward, How Few Remains' timeline is different from ours.