Fallon led a small company of Santa Cruz volunteers over the mountains and took the pueblo without bloodshed on July 11, 1846. On July 14 he raised an American flag over the juzgado. He later built the Fallon House and was mayor in 1859-60.
A statue of Fallon raising the flag, commissioned in the 1980s, was stored for years after protests that he stood for the conquest of Mexican California, displayed from 2002 in Pellier Park, damaged in 2020 and removed in 2023.