On 8 December 1941, the Japanese army attacked Hong Kong, then under British control. While the British Army fought back, it was overwhelmed by a coordinated Japanese assault on air, sea and land. The British government sent a telegram requesting help. The 12th group army, commanded by Chow and stationed in Shaoguan, was ordered to break the Japanese siege of Hong Kong. Chow set up a battle plan for Hong Kong and to protect his Canton base. Chow's fellow Nationalist general Yu Hanmou was named the commander to troops on a day and night march to Kowloon. They sent a telegram to the Hong Kong government that if the British troops could hold out until the end of December, the 12th group army would arrive to help fight the enemy, Chow's biographers wrote.