After the United States conquered California and took it from Mexico in the 1850s, there was a fairly rapid influx of new settlers. Interestingly, some of the prominent early settlers of Orange County were confederate veterans of the Civil War. Here are some of them:
-William T. Glassell, brother of Andrew Glassell, one of the founders of the City of Orange
-J.K. Tuffee, employee of Abel Stearns who owned the first general store in Fullerton. I think Tuffee Jr. High is named after him.
-John Y. Anderson, the first settler of Westminster
-Dr. Henry W. Head, early settler of Garden Grove, who later became a State Assemblyman
Another interesting bit of history is that some cities in Orange County were first founded as “Temperance Colonies.” A temperance colony was a place, usually founded by a minister or other religious figure, where alcohol was outlawed. The temperance movement is what eventually led to Prohibition. The cities of Westminster and Garden Grove were originally founded as temperance colonies.
Source: Orange County Through Four Centuries by Leo J. Friis