Which empire first used "Greek Fire" in warfare?

The Byzantine Empire was the first to use "Greek Fire" in warfare. Greek fire was an incendiary weapon used by the Eastern Roman (Byzantine) Empire beginning c. 672. Used to set enemy ships on fire, it consisted of a combustible compound emitted by a flame-throwing weapon.

Greek fire was first used by the Greeks when they were besieged in Constantinople (673–78). Originally Byzantine officials had a variety of names for Greek Fire. They would routinely call it "sea fire", "Roman fire", "war fire", "liquid fire", "sticky fire", or "manufactured fire".

The Byzantine Empire, referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire in its eastern provinces during Late Antiquity and the Middle Ages (330 to 1453 CE.), when its capital city was Constantinople. During its existence, this empire totally ruled most of Eastern and Southern Europe.