In 1853 a filibustering expedition against Sonora under William Walker took possession of La Paz and proclaimed a republic consisting of Sonora and the peninsula.
For some years there was considerable sentiment favouring filibustering in Sonora.
One outstanding incident was the filibustering expedition of William Walker, who was at first invited by the Liberals of Leon to assist them against the Conservatives of Granada, and who, after seizing the supreme power in 1856, was expelled by the combined forces of the neighbouring states, and on venturing to return was shot at Trujillo in Honduras on the 12th of September 1860.
The aftermath of Fremont's filibustering acts, followed as they were by wholly needless hostilities and by some injustice then and later in the attitude of Americans toward the natives, was a growing misunderstanding, and estrangement regrettable in Californian history.
Crittenden, members of the Bahia Honda filibustering expedition of Narciso Lopez, were shot at Fort Atares in 1851.