Dionysius the Phocaean or Dionysius of Phocaea (fl. 494 BC) was a Phocaean admiral of Ancient Greece during the Persian Wars of 5th century BC, and was the commander of the Ionian fleet at the Battle of Lade in 494 BC. Although commanding a formidable force, according to the Greek historian Herodotus, his men were worked so hard in preparing for battle that on the eve of the battle they refused to engage the Persian fleet. Dionysius himself however, continued fighting the Persians sinking three warships before being forced to retreat during the final hours of the battle.