On March 3, 1815, due to the abolition of the Constitution listing the Philippines as a Spanish province, 1,500 Ilocanos under Simon Tomas, Mariano Espiritu, Vicente Santiago and Andres Bugarin staged the Kailián Revolt in Sarrat, looting the churches and killing some friars and officials. The revolt spread to the towns of Batac, Paoay, Piddig, San Nicolas and Vintar before it was suppressed on March 6.
On a book of Carlos Quirino - Filipinos at War (1981 edition) we can read:
" The Ilocos revolt of 1815, therefore, was a class struggle that the socialist apostle, Karl Marx, would write about half a ... The leader of the rebels was a certain townsman named Domingo who held secret meetings with the kailanes of the neighboring towns of Piddig, Dingras and Vintar. ... to pounding the drums, a signal which was answered in all the houses of the kailanes by the raising of a white flag."
The adoption of a white flag as signal or symbol of revolt is not so common, white color in the Archipelago was adopted in many cases as symbol of peace, capitulation or mourning.
Maybe that white flag was just one of many flags and banners adopted during that event of 1815.... .