Mao converted to State Property and changed MOST of China's farms into workshops, leading to mass starvation.
He also built lots of forges, and then cancelled them, until eventually hammer decay made the effort completely unproductive.
Canada became a vassal state of England.
America DOWed on England once England demanded too much money to pay for their expensive wars. As a result, America threw off its vassalage and gained independence. However, they had trouble against English redcoats due to their +25% gunpowder bonus. However, woodsman III and guerrilla III muskets helped turn the tide, leading to the battle of Yorktown, where the redcoat bonus didn't matter as much because the Americans had lots of cannon, and thus collateral damage.
Persia's embassy attack event led to a -3 Past Events Have Pissed Us Off Modifier. It also led to the ending of Open Borders and all trade routes between the two countries of Persia and America. Currently, though the two countries are not at war, the modifiers are -10 and the two countries are furious with one another due to different religions, the -3 modifier, and -1 Your Spy Was Causing Trouble. Currently the Persians are trying to build a tactical nuke, which the Americans are sabotaging with spies.
The Mayans were too busy building the Chitzen Itza instead of working the land around them. As a result, the swamps re-claimed all of their territory, leading to their starvation and death.
China chopped too many of their forests, and built too many Coal Plants, leading to massive unhealthiness in their cities.
Before WWII, Italy DOWed on the Ethiopians with Rifles and got their initial stack ass-whooped by fortified Oromo Warriors. Eventually, however, the Italians brought in fighters to bombard city defenses, leading to their victory.
Aztec Jaguar Warriors were no match for Spanish Curraisers, with their higher strength value and +50% melee bonus.
The Native Americans, Aztecs, and Incans lost to the Europeans because they never scouted their surrounding territory, which meant that all three civilizations were pretty much playing in isolation. Thanks to tech trades and foreign commerce, the Europeans got a massive tech lead against pretty much everyone else, which led to the period of colonialism, once Astronomy kicked in.
The Chinese built the Great Wall, thinking that it protected them from barbarians. But the Mongols are a rival civilization, not a barbarian. So they took over China with Keshiks.
It turns out that Cho-Ko-Nus are not that effective against Keshiks.