What historic battle, if it had a different result, would have the most interesting and drastically different modern world?

For example, if the Aztecs beat the Spanish, what would the world look like today? Maybe the US wouldn’t exist, or at the very least Mexico would be a global power. Or if the golden horde was defeated at the outskirt of Europe, maybe Eastern European nations wouldn’t have been isolated from the Renaissance and would be on par culturally and socially with Western Europe.<br><br>Which conflicts do you think would have drastically changed the modern world?<br><br>(& please be historically accurate :) )