Alternative history works on the 'what if?' idea. A battle lost, a discovery never made...
Leading historians have written a few suggestions in:
'What if?: Military Historians Imagine What Might have Been' edited by Robert Cowley
'What might have been: Imaginary History from twelve leading historians' edited by Andrew Roberts
both these titles can be found at 909 in the non-fiction collection.
Alternatively many authors have taken it and done more than a chapter instead creating whole books or even worlds. For starters try:
The Truth is Dead edited by Margus Sedgwick
Collection of short stories looking at various times in history and what might have been.
The Wolves of Willoughby Chase by Joan Aiken
Alternate UK history - King James III is on the throne and although it's only 1820 steam trains already exist.
The Man in the High Castle by Philip K. Dick
The Allies lost WWII - Nazi's control New York but the Japanese have California and the middle of the US is a neutral buffer zone between these two powers.
Fatherland by Robert Harris
1964 and Adolf Hitler is about to celebrate his 75th birthday.
Hitler's War by Harry Turtledove
What if the Second World War had started in 1938? What a difference a year makes.
Resurrection Day by Brendan DuBois
What if the Cuban Missile Crisis had actually resulted in a atomic war?
