An ancient king whipped the ocean to protect his troops – and it worked
There's an old military adage that goes "if it's stupid and it works, then it isn't stupid." This idea clearly dates all the way back to the Classical Era, because the stupidest thing ever done to protect a fighting force was perpetrated in 480 BC. By a King.
Say what you want about Persian King Xerxes I, he knew how to fight a battle. That is to say, he always brought enough men and material to get the job done. Yes, this is the same Xerxes seen in the movie 300, but before the Persian Army could get to Thermopylae, they had to cross the Hellespont, what we call the Dardanelles today. It did not go exactly as planned.
Like a lot of things the Persian Army tried.
Xerxes was coming right off of victories over uprisings against Persian rule in Egypt and Babylon and had acquired a massive army, as-then-unheard-of in ancient times. Some 300,000 troops were ready to pour into Greece to avenge the ass-kicking the Greeks perpetrated on Xerxes' father, Darius. Xerxes was not one to overthink things. The simplest way to get a massive army from one land mass to another was to simply build a bridge and roads to it. Xerxes even had the bridges built in advance so his army wouldn't have to wait to get to Greece.
This did not go exactly as the Persian Army planned. Before he and his troops could arrive, the seas swelled up and swallowed the bridges, completely destroying them. When the King arrived, it was just debris. Infuriated with the seas, Xerxes marched out to the sea and whipped it with a chain 300 times as his soldiers watched and shouted curses at the water.
He also beheaded the engineers who built the bridge, which may have been a contributing factor to his eventual success.
The bridges were then rebuilt to the exact specifications required to hold 300,000 Persian troops bent on destruction, along with their pack animals, cavalry, and whatever else they could carry. This time, the bridges held and the Persians marched out to meet the Greeks – who would kick the Persian Army right back out of Europe by the following spring.
When the Persians arrived at the bridges in full retreat, they had been destroyed again.