There are two forces in history.
The first is weight. Or mass. Or trajectory. The unstoppable force. The US overtaking Britain as the premier industrial power. The two continental powers, Russia and the US, dividing Europe between them, an ancient pattern. Then the US outlasting the USSR because the US’s alliance had more people and resources and better geography.
The rise of China. The inexorable march of global warming and ecological collapse. The financialization and hollowing of a hegemonic power which always follows the decision to do free trade seriously
The second is human decision making at crisis points. Think the Cuban Missile Crisis. There were powerful men in the US who wanted to strike Cuba or Russian ships. If they had done so, there would almost certainly have been a nuclear exchange.