Here is a quick summary.
Alexander the Great had set out to conquor Persia but he faced a major obstacle- he lacked a fleet. In order to compensate for this weakness he captured all the Persian Naval bases using land forces. One of the naval bases was Tyre, but it was unique in a way that caused Alexander a lot of trouble- It was a island. To overcome this obstacle Alexander built a half a mile long causeway to the island to deploy his forces against the city. The first time he attempted to build the causway the Tyrians sent a fire ship to destroy the causway which not only destroyed it but also killed many of Alexanders troops. Alexander then accuired ships to protect the causeway during the second construction and he was sucessful. After the causway was completed Alexander deployed seige towers to crush the city walls and then he sent his infantry to finish the job, destroying the main enemy resistance. After the main resistance was defeated Alexander burned the city to the ground killing 10,000 and enslaving 30,000.