Basically Tyre was a famous island with a huge port and it was this massive trade center
On the nearby mainland, Alexander the Great was like "I'm finna conquer this island"
One problem: he didn't have enough ships to fully lay siege to it
So what he does is take a bunch of military garbage (old war engines and whatnot) and throws enough of it into the sea that he creates an entire bridge to reach Tyre
Then he wheeled his siege engines across the bridge to take the city
The end