The battle is notable for the peculiar role played by a detachment of 200 Japanese samurai who fought on behalf of the Union forces. The samurai, sent by the declining Tokugawa Shogunate to acquire Western knowledge, were attempting to travel to Harvard University in Massachusetts, which was recognized by the shogunate as a top-tier university.

The samurai, who had departed Japan prior to the outbreak of hostilities, landed at San Diego and found themselves caught up in the conflict. After learning that Confederate militias were attempting to cut California's contact with the North, the samurai came to Wright's assistance. Wielding their traditional curved katana swords, the samurai surprised the rear of Showalter's force, claiming no fewer than 30 severed heads, and ending Confederate pretensions to holding the far west.

https://en.wikipedia.org/wiki/Battle_of_Camp_Wright

(http://www.autoadmit.com/thread.php?thread_id=3512617&forum_id=2#32523170)