It was at the Yunnan Military Academy in Kunming that he first met Cai E (Tsai Ao).
He taught at the Academy after his graduation in July 1911.
Siding with the revolutionary forces after the Chinese Revolution, he joined Brig.
Cai E in the October 1911 expeditionary force that marched on Qing forces in Sichuan.
He served as a regimental commander in the campaign to unseat Yuan Shikai in 1915–16.
When Cai became governor of Sichuan after Yuan's death in June 1916, Zhu was made a brigade commander.

Following the death of his mentor Cai E and of his first wife Xiao Jufang in 1916, Zhu developed a severe opium habit that afflicted him for several years until 1922, when he underwent treatment in Shanghai.
His troops continued to support him, and so he consolidated his forces to become a warlord.
In 1920, after his troops were driven from Sichuan toward the Tibetan border, he returned to Yunnan as a public security commissioner of the provincial government.
Around this time he decided to leave China for study in Europe.
He first traveled to Shanghai, where he broke his opium habit and, according to historians of the Kuomintang, met Dr. Sun Yat-sen.
He attempted to join the Chinese Communist Party in early 1922, but was rejected for being a warlord.
It was at the Yunnan Military Academy in Kunming that he first met Cai E (Tsai Ao). He taught at the Academy after his graduation in July 1911. Siding with the revolutionary forces after the Chinese Revolution, he joined Brig. Cai E in the October 1911 expeditionary force that marched on Qing forces in Sichuan. He served as a regimental commander in the campaign to unseat Yuan Shikai in 1915–16. When Cai became governor of Sichuan after Yuan's death in June 1916, Zhu was made a brigade commander.
Following the death of his mentor Cai E and of his first wife Xiao Jufang in 1916, Zhu developed a severe opium habit that afflicted him for several years until 1922, when he underwent treatment in Shanghai. His troops continued to support him, and so he consolidated his forces to become a warlord. In 1920, after his troops were driven from Sichuan toward the Tibetan border, he returned to Yunnan as a public security commissioner of the provincial government. Around this time he decided to leave China for study in Europe. He first traveled to Shanghai, where he broke his opium habit and, according to historians of the Kuomintang, met Dr. Sun Yat-sen. He attempted to join the Chinese Communist Party in early 1922, but was rejected for being a warlord.
Zhu De