As early as March 6, 1899, Apolinario Mabini, in his capacity as premier and minister of foreign affairs, met with the Schurman Commission. The commission had offered the Filipinos some form of autonomous government. Mabini’s request for time to consult the people on the offer and a ceasefire in the meantime was refused. Mabini made another attempt, which turned to be futile, to seek an armistice on April 28. He later issued a manifesto criticizing the Americans, whom he described as a free people trying to rob others of their liberty. He then rallied the Filipino people to go on with the fight against the Americans.

When Mabini resigned from his post on May 7, 1899, President Aguinaldo named Pedro A. Paterno to head a new cabinet. It was Biak-na-Bato all over again. Notified of his replacement by Paterno, Mabini scoffed at the negotiations of the new cabinet on the basis of autonomy, calling it a desire for “independence without any struggle.” As expected, nothing came out of the Paterno peace efforts because the U.S. insisted that the Filipinos lay down their arms first.

Disunity Among the Filipinos.

Among the military and political leaders, disunity again caused divisions. Although they were in a war against a common enemy, many of their leaders in the government and in the army sadly still found time to engage in personal, and often bitter quarrels, with disastrous and tragic consequences to the First Philippine Republic. The power struggle served to weaken Filipino unity at a time of great peril to the nation.

Apolinario Mabini was considered an obstacle who was put out of the way with his resignation on May 7, 1899, by those who were later named to the Paterno cabinet. But a more formidable obstacle was General Antonio Luna, who was recognized as the ablest general of the revolution. Earlier, he was one of those who had revealed the existence of the Katipunan to the Spaniards.

A well-off ilustrado, Luna had joined Aguinaldo in 1898 and proved his worth as an officer. As a result, he was appointed commander-in-chief for central Luzon when the Filipino-American hostilities erupted.

However, he had a volatile temper and sharp tongue. He was very vocal against entering into any deal with the Americans; he opposed autonomy and strongly advocated a fight for independence. He even arrested members of the Paterno cabinet after he learned that they were planning to negotiate with the Americans, calling them traitors. Turned over to Aguinaldo, the Cabinet members were turned loose as soon as Luna left. These men then poisoned the mind of Aguinaldo against Luna, saying the hot-headed general was eyeing the presidency. In reality, Luna was only trying to get popular support for his arrest of the Paterno cabinet and to drum up opposition to autonomy.

Here’s how Luna was killed as narrated in the book History of the Filipino People by Teodoro Agoncillo and Milagros C. Guerrero:

Upon Aguinaldo’s invitation, General Luna on June 5, 1899, went to a convent in Cabanatuan, Nueva Ecija, which served as Aguinaldo’s headquarters. When he arrived, Aguinaldo had already left for San Isidro, Nueva Ecija. Luna slapped the sentry at the convent as he went upstairs. There, he saw Felipe Buencamino, whom he despised, and they exchanged heated words. A rifle shot was heard from downstairs. He rushed downstairs, and there, members of the Kawit Company, one of whom he had recommended for punishment, mobbed him. Several stabbed him with daggers; others shot at him. He was able to run to the street. He fired his pistol, but he didn’t hit anybody. Colonel Francisco Roman, his aide-de-camp, came to his defense, but he was shot to death. As he fell on the convent yard, all Luna could say was, “Cow....ards! As...sas...sins!” The next day, he was buried with military honors. However, no soldiers were investigated for the killing.

The killing of Luna was a big blow to the cause of the Filipinos. It was, as Constantino puts it, “Bonifacio’s fate repeated.” His death deprived the nation of an able militarist. After Luna’s death, Aguinaldo ordered all chiefs of brigades under Luna arrested. He also ordered the disarming of two companies suspected of being pro-Luna. Such acts, especially the slaying of Luna, led to the demoralization of the army, as he had had a wide following.

Source
The Filipino Americans (From 1763 to the Present): Their History, Culture, & Traditions.
Veltisezar B. Bautista