In 1935, Kim took the name "Kim Il-sung", meaning "Kim become the sun". Kim was appointed commander of the 6th division in 1937, at the age of 24, controlling a few hundred men in a group that came to be known as "Kim Il-sung's division". While commanding this division, he executed a raid on Poch’onbo, on 4 June 1937. Although Kim's division only captured the small Japanese-held town just within the Korean border for a few hours, it was nonetheless considered a military success at this time, when the guerrilla units had experienced difficulty in capturing any enemy territory. This accomplishment would grant Kim some measure of fame among Chinese guerrillas, and North Korean biographies would later exploit it as a great victory for Korea. For their part, the Japanese regarded Kim as one of the most effective and popular Korean guerrilla leaders. He appeared on Japanese wanted lists as the "Tiger". The Japanese "Maeda Unit" was sent to hunt him in February 1940. Later in 1940, the Japanese kidnapped a woman named Kim Hye-sun, believed to have been Kim Il-Sung's first wife. After using her as a hostage to try to convince the Korean guerrillas to surrender, she was killed. Kim was appointed commander of the 2nd operational region for the 1st Army, but by the end of 1940 he was the only 1st Army leader still alive. Pursued by Japanese troops, Kim and what remained of his army escaped by crossing the Amur River into the Soviet Union. Kim was sent to a camp at Vyatskoye near Khabarovsk, where the Soviets retrained the Korean communist guerrillas. In August 1942, Kim and his army were assigned to a special unit known as the 88th Separate Rifle Brigade, which belonged to the Soviet Red Army. Kim's immediate superior was Zhou Baozhong. Kim became a Major in the Soviet Red Army and served in it until the end of World War II in 1945.