The Imperial Japanese Army launched a major offensive into Guangxi province with the intention of eliminating the Chinese supply route through French-controlled Vietnam. The elite Japanese 5th Division was given the task of spearheading the Japanese offensive. After occupying Nanning in November 1939, the Japanese captured the key point of Kunlun pass and were poised to attack the Chinese forces that protected Chungking, the wartime capital. Realizing that inaction would result in being cut off, General Bai Chongxi, himself a native of Guangxi, asked the Nationalist Government for reinforcements. Chiang Kai-shek in turn, dispatched the 5th Corps from Hunan province to fight the Japanese. The 5th Corps was the most elite unit in the NRA, and it is also the only Chinese unit that had tanks and armored vehicles. Its soldiers were combat-hardened veterans from previous engagements against Japanese forces, and as a result, morale was high. General Du Yuming, commander of the 5th Corps, dispatched two divisions to attack the Japanese-held Kunlun Pass. The New 22nd Divisions attack ended up cutting off Japanese reinforcements from the rear and also resulted in the death of the Japanese commander, Major General Masao Nakamura. The Japanese reacted immediately by sending in the elite unit of the Japanese 5th Division, the 21st Brigade, which had also participated in the Russo-Japanese War, nicknamed the "unbreakable sword". Faced with the serious possibility of being completely cut off, the Japanese army ended up relying on air power to for the delivery of vital supplies. Before Major General Nakamura's death, he admitted in his diary that the Chinese soldiers' fighting ability had surpassed the Russians whom the Brigade encountered in Manchuria. This campaign was the first major victory of the Chinese army since the Battle of Wuhan. At a cost of 14,000 casualties, the Chinese army had inflicted a total of 10,000 casualties on the Japanese. Among the Japanese casualties were 5,000 fatalities, including over 85% of all officers, such as Major General Nakamura, Colonel Sakata Gen'ichi, Colonel Miki Kichinosuke, Colonel 生田滕一, 杵平作, 官本得, 森本宮, among others. Additionally, the Chinese took 102 Japanese troops as prisoner, and captured 79 horses, 10 mountain guns, 12 field guns, 10 anti-tank guns, 102 light machine guns, 80 heavy machine guns, and 2,000 rifles.
