The Action of 18 October 1806 was a minor naval engagement during the Napoleonic Wars, fought between the British Royal Navy frigate HMS Caroline and a Dutch squadron at the entrance to Batavia harbour on Java in the Dutch East Indies. During the battle the Dutch frigate Maria Riggersbergen was left unsupported by the remainder of the squadron and, isolated, was forced to surrender. Captain Peter Rainier, the British commander, was subsequently free to remove his prize from within sight of the Dutch port when the remainder of the Dutch squadron refused to engage Caroline and their crews deliberately grounded the ships to avoid capture. He also returned many prisoners taken previously in a captured brig.