Final answer:
John Paul Jones is the U.S. naval commander who famously responded, "I have not yet begun to fight" during the American Revolution.
Step-by-step explanation:
The U.S. naval commander who famously responded, "I have not yet begun to fight" was John Paul Jones. He was an American naval officer during the American Revolution. When his ship, the Bonhomme Richard, engaged in battle with the British ship HMS Serapis in September 1779, the British captain asked Jones if he was surrendering. Jones defiantly replied, "I have not yet begun to fight." Eventually, the Bonhomme Richard emerged victorious, despite suffering heavy damage.