The friction came to a head in 1836, when Monterey-born Juan Bautista Alvarado led a revolt against the 1836 constitution, seizing control of Monterey from Nicolás Gutiérrez. Alvarado's actions nearly led to a civil war with loyalist forces based in Los Angeles, but a ceasefire was arranged. After an unsettled period, Alvarado agreed to support the 1839 constitution, and Mexico City appointed him to serve as governor from 1837 to 1842. Other "Californio" governors followed, including Carlos Antonio Carrillo, and Pío Pico. The last non-Californian governor, Manuel Micheltorena, was driven out after another rebellion in 1845. Micheltorena was replaced by Pío Pico, last Mexican governor of California, who served until 1846 when the U.S. military occupation began.