Editor's Note: To celebrate the 100th founding anniversary of the Communist Party of China, we are launching the "100 CPC Stories in 100 Days" series, featuring foreigners who witnessed and participated in the CPC's history and helped the world better understand the CPC. The following is the fourth story of the series.

On July 7, 1942, five years after China began a full-scale war of resistance against Japanese aggression, a young Indian doctor solemnly swore to the red flag to join the Communist Party of China (CPC). He was then on the battlefront of the Shanxi-Chahar-Hebei border region. After taking the oath, he declared excitedly that he would fight with the army and the people in the liberated areas till his last breath. His name was Dwarkanath Kotnis, or Ke Dihua in Chinese. The soldiers of the Eighth Route Army and the villagers liked to call him Old Ke.

Old Ke's bond with China began with a letter from Zhu De, then Commander-in-Chief of the Eighth Route Army, to Jawaharlal Nehru, the leader of the Indian National Congress, asking for material and medical assistance from India. The Army was in acute shortage of doctors and medicine as the war raged on in China. Upon receiving the letter, the Indian side immediately assembled and sent a medical team of five doctors to China amid the flames of war. Dr. Kotnis was one of them.