Oops!

 

One of the more embarrasing incidents in American military history occurred on October 8-9, 1842.  Commodore Thomas ap Catesby Jones, commander of the Pacific Squadron, acting upon rumors that the United States and Mexico were going to war, and that Mexico would cede California to Great Britain, seized the town of Monterey, California, on October 8, landing 50 Marines and 100 sailors.  No blood was shed in the takeover.

Commodore Jones quickly learned that none of the rumors were true:  the US and Mexico were not at war and Mexico had no intention of giving California to Great Britain.  Jones withdrew his Marines and sailors on October 9, 1842 and sailed away to Hawaii where he restored the native government which had been toppled by the British.  American apologies over the Monterey Incident were profuse, but the Mexicans were naturally disturbed, and the Incident materially worsened the relationship between the two nations and quickened the slide to war.