An original member of the Katipunan movement, he fought alongside Andres Bonifacio throughout the Philippine Revolution of 1896. In 1899 he continued the struggle for Philippine independence against the United States. Near the end of the Philippine American War Sacay was captured and jailed by the Philippine Constabulary. After the surrender of the last Filipino Commanding General Miguel Malvar in April 1902, President Theodore Roosevelt officially ended the Philippine American War on July 4, 1902. With the end of the war, Sacay was granted amnesty and released from prison. On November 12, 1902 the Philippine Commission passed the Bandolerism Act which proclaimed all captured resistance fighters or insurgents to be tried in court as bandits, ladrones, and robbers. In April 1904, Sacay issued his own manifesto proclaiming himself President and established his own government called Republika ng Katagalugan (the Tagalog Republic) in opposition to U.S. colonial rule. The U.S. Government does not recognize Sacay's government and through the Bandolerism Act labels him an outlaw. The Governor General, the U.S. Government, and the U.S. military leave the pursuit of Sacay in the hands of the Philippine Constabulary and Philippine Scouts. In 1905 concentration camps, often referred to as Zonas, are re-established in parts of Cavite, Batangas, and Laguna. This has little effect on Sacay and his freedom fighters. Extensive fighting continues in Southern-Luzon for months.
On 14 July, 1906, after receiving a letter from the American governor-general promising amnesty for himself and his men in exchange for surrender, Sacay, one of the last remaining Filipino generals, finally surrendered.