questioning the political, religious, and economic order. In May 1896, Pio affiliated with the Katipunan and organized a chapter in Culi-Culi which was called Magtagumpay. Elected as secretary, he picked Pang-una as his nom-deguerre. When the guardia civil began monitoring his movements, he changed his name to Pio del Pilar to safeguard his family-but not soon enough. The authorities had already closed in on him. They tortured him so that he would reveal the nature and roster of the society, but the Spaniards failed to extract any secret from him.

On August 29, 1896, Pio had his first encounter with Spanish troops in Mandaluyong. In November he led an army of Caviteños to recapture the town of Binakayan. On February 16, 1897, del Pilar, now a colonel, defended Bacoor and Las Piñas. He was soon promoted to brigadier general.

On March 17, at the Naic Assembly in Cavite, Andres Bonifacio appointed Pio del Pilar as military commander of an army corps in a move to establish a government other than the one previously proclaimed in Tejeros. After Bonifacio's death he joined the Magdalo faction and as a general served under Emilio Aguinaldo.

As provided in the Pact of Biak-na-Bato, Pio and other generals surrendered their arms to the Spaniards. When the Spanish-American War broke out, the new governor-general, Basilio Augustin y Davila, in his earnest efforts to institute reforms in the islands, formed militia units composed of amnestied insurgents, on whom military ranks were conferred. A number of redoubtable figures in the Philippine Revolution declared themselves on the side of the Spanish Army, among them Mariano Trias, Emiliano Riego de Dios, Artemio Ricarte, and Pio del Pilar. But when the Americans showed up on Manila Bay Augustin left in a hurry and del Pilar rejoined Aguinaldo to fight the Americans alongside his former chief.

Immediately after rejoining Aguinaldo , Del Pilar recommended that Filipino troops adopt the formal name of "The Liberating Army of the Republic of the Philippines ." Aguinaldo liked the idea, but kept referring to the movement as "The Revolution."

But if Aguinaldo was not taken by del Pilar's way with words, he had implicit trust and a frank admiration of the latter's courage and leadership. When Aguinaldo devised a system of zoning each province into a military area, he appointed del Pilar as one of four zone commanders. Only one other officer was higher than all four of them: Antonio Luna who, as Director of War, was in effect supreme commander of the army.