Greek fire was developed by a Greek-speaking Syrian refugee in 650 AD. Comprised of naphtha, sulfur, saltpeter, quicklime, and petroleum, Greek fire burned on contact with water. Perhaps its most spectacular moment came when the Byzantine emperor Alexius I Comnenus burned down a Pisan fleet in the eleventh century. The Emperor had ordered each of his ships set with a lion's head made of iron or bronze. Tubes fed through the lions' mouths into containers of Greek fire so that when battle commenced, the lions appeared to be "vomiting fire".