Squatter riots of the 1850s
Californios have land grants. City claims land. City claims more land, including Californio land. CIty un-claims land that has people on it. Squatters now have legal rights to Californio land.
Riots!
https://en.wikipedia.org/wiki/Squatters%27_riot
An 1864 Congressional Act permanently settled land disputes brought on by the Van Ness Ordinance