Sandatahan

The Sandatahanes (plural, from Tagalog sandatahan ), also known as bolomen, were lightly armed, often irregular units within the Philippine Republican Army. It was officially called Cuerpo de Armas Blancas (Knife Corps in English). Typically equipped with a bolo knife, they served primarily to support the regular forces. Dressed as farmers or civilians during the day, the Sandatahanes engaged in guerrilla activities at night, including ambushing small detachments of enemy soldiers, sabotage, and, most importantly, supplying the regular army with intelligence on enemy positions and movements. The unit traces its history back to the lightly or even unarmed Katipunan revolutionaries during the war of independence from Spain.

The Sandatahanes played significant roles in the opening phases of the Philippine-American War, notably in the the Battle of Manila in 1899 and the Second Battle of Caloocan.

Notable Units
A regiment had already been in existence in Tondo and Binondo between December 1898 and January 9, 1899 and may have been originally organized to act against Spanish colonial authorities. Led by Colonel Luciano Lucas, the unit was independent of the main force outside the city. Although it was created to enforce the interests of the Malolos Government, it operated with significant independence from the high command and the main force. The exact strength of the unit remains unknown, but Colonel Lucas' letters suggest he commanded an entire regiment. Dean C. Worcester estimates it to be composed of 6,330 men. General Otis, on the other hand, said that this force had been reported to him as being 10,000 men. The unit's mission before the war's outbreak was ambiguous. Lucas claimed it was formed to collect contributions from wealthy Manila residents, guard against American abuses, and perform other important services. He stated that the unit aimed to maintain peace and tranquillity for native Filipinos in Manila and would only collect funds necessary for sustaining the battalion.

On February 17, 1899, while moving to an operational area to join an attack, the unit captured Gregorio Martinez, who had informed the Americans of their presence. Aware of the imminent danger, the unit discarded their arms and abandoned their advance. Martinez's fate is not mentioned.

The operations of this unit also included the kidnapping of Filipinos seen with Americans, as reported by a Filipino agent codenamed "Pipi". The unit's operational efficacy declined as Filipino forces were pushed further from Manila and more American troops arrived in the city.

During the Second Battle of Caloocan, male guerrilla operatives infiltrated the American lines disguised as women and successfully set fire to the suburb of San Fernando de Dilao in Manila. However, their efforts were only partly successful and were quickly suppressed by the American provost guards as well as lack of coordination and support from the city's residents.

Organization
Several units were formed between 1899 and 1901, namely:
 * Guerilla de Voluntarios, an all-volunteer guerilla unit
 * Guerilla Montada, a mounted guerilla unit
 * Guerilla Navotas, a guerilla unit that operated in and around the town of Navotas
 * Zona de Manila, a guerilla unit that operated within the city of Manila and participated in the Battle of Manila in 1899 and the Second Battle of Caloocan