Why did Filipino forces switch to guerrilla warfare in 1899?

Filipino forces shifted to guerrilla warfare in November 1899 primarily because they were unable to defeat the United States in conventional, orthodox battles.12

Following the outbreak of the Philippine-American War in February 1899, Filipino troops suffered significant defeats at the hands of better-equipped American forces. After the loss of their capital, Malolos, and facing the arrival of U.S. reinforcements, the Filipino government was forced to flee northward.132

By adopting guerrilla tactics, the Filipino leadership sought to continue their resistance through a strategy of protracted harassment, utilizing mobility and surprise to wear down the American military presence. This shift marked a transition from the failed attempt at conventional military defense to a decentralized campaign of insurgency that persisted for several years, even after the capture of Emilio Aguinaldo in 1901.142