As a leader of the resistance, Thảo was allocated the responsibility of indoctrinating the 1947 batch of recruits with Vietminh ideology. One of Thảo's students was his future enemy, South Vietnamese General and President Nguyễn Khánh. This group became the 410th Battalion and went on to fight near Cà Mau, the southernmost part of Vietnam. By 1949, Thảo was in charge of the Vietminh espionage apparatus around Saigon and organised the guerrilla companies in the countryside. Thảo was also involved in procuring arms. Filipino traders brought arms into southern Vietnam in return for rice, shrimp, pork, gold and banknotes. Following the French defeat in 1954 at Điện Biên Phủ, Thảo helped evacuate communist fighters from South Vietnam and Cambodia in accordance with the terms of the Geneva Conference. Under these Accords, Vietnam was to be temporarily divided at the 17th parallel pending national elections to reunify the country in 1956, and military personnel were to be evacuated to their respective sides of the border. In the meantime, Hồ Chí Minh's Vietminh controlled the north under the DRV while the south was under the French-sponsored State of Vietnam.