In 1905, he left Vietnam to study at military academies, first in Japan and then in China, as part of Phan Bội Châu's Đông Du (Travel to the East) movement.

[1] In 1912, he joined Châu's Vietnam Restoration League (Việt Nam Quang Phục Hội) and became one of its representatives in Guangxi[2] and one of its most capable military leaders.

[3] After Châu's capture in 1925 that led to the league's demise, Thần and other revolutionaries in China founded the Việt Nam Cách Mạng Đồng Minh Hội.

[4] Using his good relationship with Chiang Kai-shek, he lobbied for the release and pardon of Hồ Chí Minh when the latter was in jail waiting to be executed for "crimes against the French colonial government".

As soon as the Chinese troops that had entered Vietnam to disarm the Japanese were replaced by French expeditionary forces, Hồ's Việt Minh attacked all non-communist bases in the country.