[6] The retreat of Aguinaldo from Bayambang, through the mountainous terrain began on November 13, 1899, after he had disbanded the regular Filipino army into guerrilla units.

[2] The hand-picked force of Filipinos, which was the remaining contingent of Antonio Luna's army, constructed several sets of trenches and stone barricades on both shoulders of the pass, as well as on top of its 4,500-foot (1,400 m) height.

[2] On the morning of December 2, the Americans advanced up the trail but were met with a steady volley of fire, enabling them to climb to only around 300 feet.

Texan sharpshooters positioned themselves on a hill overlooking the trenches, whittling down the Philippine rear guard with measured volleys.

[2][8] March then sent elements of their force with an Igorot villager named Januario Galut to determine the Filipino positions and outflank the defenders.

[2] Among the dead was General del Pilar, shot through the neck at the height or end of the struggle (depending upon which eye-witness account is to be believed).

[2] Among the 60 Filipino soldiers, only eight survived, namely Colonel Vicente Enriquez, Captain Juan H. Del Pilar, Lieutenant Telesforo Pérez Carrasco, Lieutenant José Enriquez, "Juanchito" Del Pilar, Emilio Garcia, Iñigo De Jesus, and one unnamed officer.

[citation needed] Upon receiving word of the battle outcome from Lieutenant José Enriquez (Colonel Enriquez's younger brother) and "Juanchito" Del Pilar (General Gregorio Del Pilar's cousin)[citation needed] in nearby Cervantes, Ilocos Sur, Aguinaldo and his party resumed their retreat into the mountains of what was then Bontoc province, pursued by March and his men.

In his critical book of essays A Question of Heroes he notes that Tirad Pass was an "exercise in futility" in that it only allowed Aguinaldo to "run to nowhere".

[11] Del Pilar's diary was recovered among the possessions looted by the victorious Americans, who had stripped him bare of his military decorations, his uniform and his personal belongings, leaving him, as the eyewitness, correspondent Richard Henry Little wrote, "We carved not a line and we raised not a stone, But we left him alone with his glory".