Commodore Thomas Jones

In the autumn of 1842, as Commodore Thomas Jones of the U.S. Navy led a small squadron off the coast of Peru, he received a report that the US and Mexico were at war. The report was erroneous, but Jones very much wished to believe its veracity, perhaps envisioning a bit of glory. He promptly headed north for Monterey, which, like the rest of California, was ruled by Mexico. Upon arrival in the bay, he was told, "Nope, no war," or words to that effect. He didn't listen. Instead, he pointed his cannon at the town and demanded surrender. The local Californios lowered their flag, unhappily, and Jones celebrated, briefly. He soon found some newspapers that convinced him of the absence of war, and he and his ships hastily departed.
(Photo: in the public domain from amazon.com)