What was the biggest mistake of Alexander the Great in his invasion

 After securing a massive empire, Alexander pushed into what is now Afghanistan and Pakistan around 327 BC.

He expected quick victories similar to his campaigns in Persia and Egypt.

However, what he encountered was a totally different ball game.

The geography itself was a formidable opponent—harsh, unforgiving terrain that wore down his troops. But it wasn’t just the mountains and deserts that gave him grief; the local tribes were fierce warriors who weren’t too keen on being ruled by an outsider. They resisted, and they resisted hard.

One of the most telling incidents was at the Sogdian Rock, a fortress located in today’s Uzbekistan.

When Alexander’s troops reached it, the defenders shouted down that if he wanted to capture the fortress, he’d need men with wings.

Alexander, never one to back down from a challenge, assembled a team of climbers who scaled the cliffs under cover of darkness.

They didn't exactly have wings, but they sure surprised the defenders and secured the fortress. Shows how outside the box, Alexnder used to think.

And then there was the situation with his own troops.

By the time Alexander reached the Beas River in India, his men were exhausted, homesick, and frankly, just over it.

They’d been fighting non-stop for years and were far from their families and homes. When Alexander ordered them to march further into India, they finally put their foot down, refusing to go on.

This mutiny by his own troops was a stark reminder that, perhaps, his ambition had stretched them too thin.

So yeah, Alexander was great, but he tried to take that greatness to a great length which fired back.