Although the Japanese government didn't express willingness to help the Filipino revolutionaries due to their reluctance to offend the Americans, there were a number Japanese civilians, political leaders, and officials who supported Philippine Independence.
Pan-Asianism, a movement in East, South, and South East Asia that promotes solidarity, and cooperation among Asian peoples. The belief of Asian values taking precedence over Western values, and resistance to Western imperialism and colonialism has been the motivations of this movement.
A few months after the Filipinos learned of the American deception, Mariano Ponce, the representative to Japan, had met and befriended Sun Yat Sen, a revolutionary leader aiming to overthrow the Qing dynasty.
After failing to get official support from Japan, Ponce approached Sun Yat-sen, who saw the liberation of the Philippines as a way to demonstrate Pan-Asian solidarity. He also saw the islands as a good location for a revolutionary base for his movement to stage uprisings in China.
It was also at this time where Ponce is introduced to Inukai Tsuyoshi, a leader of Japan's Progressive Party. He was as enthusiastic as Sun Yat-sen to help the Filipinos in their struggle for independence as he is also associated with the Pan-Asian movement thus his support for greater Asian solidarity. He also thought that Japan had much to gain from two grateful nations as he is also aiding Sun Yat-sen in his revolution against the Qing dynasty.
Although Inukai did want to help, he also didn't want to antagonize the Americans and ruin Japan's relations with the United States. Their plan thus went to placing Sun Yat-sen at the center of negotiations making it seem like the project of aiding the Filipinos has Chinese backing.
As their talks went on Sun introduces Ponce to Jose Ramos Ishikawa, Toten Miyazaki, and Nakamura Yaroku who assisted Ponce in purchasing the weapons and ammunitions for the revolution.
Some people in the Japanese Army, and few politicians also expressed sympathy for the Filipino revolutionaries and called for all-out aid and moved to secure weapons, and permission to send arms to the Philippines
A general in the Japanese army helped in convincing the Ministry of Foreign affairs to permit Nakamura to buy arms for the Filipinos thus giving the greenlight for the purchase.
Afterwards, Nakamura Yaroku proceeded with the purchase through arms trader, Okura Kihatiro, with the total amounting to Y155,000. This amount included with it the purchase of a steamship called the Nunobiki Maru to transport the shipment to the Philippines
The shipment was composed of 10,000 rifles, six million rounds of ammunition, a single fixed cannon, ten field guns, seven field glasses, pressing machines for gun powder and ammunition, and other military supplies.
Initially the only weapons that were available to be purchased were the ones imported from the United States, but eventually they were also able to purchase the newer and more powerful Murata rifles from a Japanese trader.
The purchases of the weapons, and supplies were very discreet where it was silently sold to a Japanese company then sold to a German friend of Nakamura until the items departed Nagasaki, Japan towards the island then known as Formosa in order to avoid the American blockade
Aside from officials aiding in purchasing weaponry, a number of Japanese soldiers organized a volunteer group, under the leadership of Captain Hara Tei, in order to fight alongside the Filipino revolutionaries. They organized their own expedition and arms delivery then left Japan a few weeks after Nakamura and Ponce's war materials were shipped to the Philippines.
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June 1899 - Aparri, Cagayan.
The Nunobiki Maru managed to avoid the American blockade and docked at the port of Aparri. The crew of the steamship is welcomed by soldiers under Manuel Tinio, who were assigned to defend the provinces of Ilocos Norte, and Cagayan.
General Aguinaldo is then informed of the successful arrival of the war materials from Japan. Aguinaldo then ordered these weapons to be distributed throughout the islands giving priority to the defenders in Luzon.
The defenders in Mindanao are given a relatively huge chunk of the cargo due to the very complicated circumstances around the islands of the Visayas, to the frustration of the defenders there.
Fortunately for them, the second shipment also arrived safely in Aparri at around the same time Captain Hara Tei and his companions landed in the town. The Japanese volunteers managed to get in contact with Aguinaldo and helped with the plans to smuggle the weapons to the defenders in the Visayas.
The arrival of the Japanese volunteers is a huge help to the Revolutionary Army as they immediately started training the Filipinos in warfare, and in using the Murata rifles. They also helped in planning, and defending Paranaque, and the hill known in modern times as Fuerte de Bonifacio which surprisingly managed to hold-out despite several months of fighting.
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Due to the huge help the Filipino forces received from the Japanese, Filipino Generals across the archipelago sent letters of appreciation saying that the Filipinos are very grateful and will never forget the support the Japanese gave to the people of the republic. Any doubt they had about the Japanese has completely disappeared.
The Junta in Hongkong, headed by Aguinaldo, expressed their utmost gratitude to Sun Yat-sen for his support in convincing Japanese officials to permit Ponce to purchase weapons. They also expressed their gratitude to Sun for his demonstration of Pan-Asian solidarity.
Lastly, the Junta presented Sun Yat-sen Y100,000 and a promise that the Philippine Republic, should it emerge victorious in its struggle against the Americans, will support Sun in his revolution against China's Imperial Dynasty.
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The aid and support of the Japanese, the support of Sun Yat-sen, and the arrival of the Japanese volunteers brought with it the idea of Pan-Asianism in the Philippines. Due to the betrayal of the Americans, Aguinaldo and his men vowed to never again trust the the words of the white man and aligned his government closely with the new found friends of the Philippine Republic.