Mass migration of Filipinos to the United States began in the early 20th century due to Filipinos being U.S. Nationals. These included Filipinos who enlisted as sailors of the United States Navy, pensionados, and laborers. During the Great Depression, Filipino Americans became targets of race-based violence, including race riots such as the one in Watsonville. The Philippine Independence Act was passed in 1934, redefining Filipinos as aliens for immigration; this encouraged Filipinos to return to the Philippines and established the Commonwealth of the Philippines. During World War II, the Philippines were occupied leading to resistance, the formation of segregated Filipino regiments, and the liberation of the islands.