What if...

1) Napoleon never invades Russia, it takes a lot longer for the British, Spanish, Russians, Austrians, Prussians to kill off the hundreds of thousands of French soldiers that died on the Russian expedition, and in the meanwhile Napoleon fortifies his Napoleon Dynasty, pounds the revolts from other countries, his exile to Elba never occurs, The Count of Monte Cristo never gets written for the lack of its triggering historical theme, France defeats England and Prussia with the help of Italy in Waterloo, Industrial Revolution never occurs or occurs in France because England ceases to exist, Napoleonic Empire becomes the Second HRE, growth of democracy and European political unrests never happen in the 19th century, and without England to bother her, China becomes another world power, fighting with France only to kill off the remaining adherents of the Napoleonic Empire, and within months/a year or two, China takes over the world with its manpower.

2) Guan Yu says to Cao Cao, "screw you," annihilates him and his army at the Red Cliff, the only dominant forces left are Wu and Shu, Shu unifies China with the might of Zhuge Liang/other generals, southern and northern dynasties period never happens, Buddhism never rises to higher status because the rulers are obsessed with Confucian and Daoist values, Buddhism never gains its largest number of adherents in history and dies off in China. Later, Mongols never find an apt official religion of the Yuan Empire with the absence of Buddhism, allows complete religious freedom for all and China becomes a nation comparable to the 21st century United States.

3) the Spanish Armada defeats Sir Francis Drake, Spain remains the dominant sea power, England never begins its colonization in America, the Revolutionary War never happens, the US never comes into existence, and without pilgrims to start the Thanksgiving tradition, we don't have Thanksgiving feasts.