No man is an island, but it turns out all Alexander the Great needed to take over an entire island was a little help from Mother Nature.

A half-mile-long spit of sand once linked the ancient Lebanese island of Tyre to the mainland, according to a new study of the area's geological history. Alexander used the natural sandbar to build a causeway, allowing his army to overwhelm the island stronghold during a siege in 332 BC.

Alexander's conquest of Tyre has long been known to archaeologists, but they never understood how he managed to build a viable overwater passage to the enemy. The challenge probably troubled the Macedonian king at first too, said study leader Nick Marriner of the CEREGE-CNRS, a French geosciences research institute...

Details of the study are in the latest edition of the Proceedings of the National Academy of Sciences.