This was the flag of his supposed clients who were still fighting the Spanish in their war for independence at the time. The United States, which had plans to annex the peninsula, sent a naval force which captured Amelia Island on December 23, 1817.
At the time, this was the emblem of his purported clients who were continuing to resist Spanish rule in their quest for independence. The United States, with plans to absorb the peninsula, sent a naval expedition that captured Amelia Island on December 23, 1817.