Japanese offensive, both the 14th Air Force and the Chinese Air Force's 4th Air Group flying P-40s and P-43s provided air support to the Chinese ground troops. The 4th Group went into action on 19 May with 8 P-40Es and 4 P-43s escorting A-29 Hudson bombers over the enemy positions. On this mission, the Deputy Group Commander Xu Baoyun, flying a P-40E, was shot down by anti-aircraft gunfire. On 31 May Lieutenant-Colonel John Alison, an American ace and two USAAF wingmen led seven P-40s from the 4th Air Group escorting nine B-24 bombers to Yichang; Alison's P-40 was badly shot up by Captain Ohtsubo Yasuto, leader of the 1st Chutai (squadron) of the 33rd FR. Lieutenant Tsang Hsu-Lan, nicknamed "Bulldog" (plane No. 2304) of the 4th Group shot down Ohtsubo, saving Alison's life. Tsang was awarded the American Silver Star as well as China's highest decoration. On 6 June, eight Japanese light bombers escorted by 14 fighters were on a raid on Liangshan. 13 P-40s from the Chinese Air Force led by Colonel Li Hsiang-yang were returning to Liangshan from a mission. Having just landed, Captain Chow Chin-kai, commander of the 23rd Squadron and veteran of many years combat ran from his P-40 to a P-66 parked nearby, and took off to attack the Japanese formation. While the Japanese fighters were strafing the airfield, Chow attacked the bombers and destroyed three. Despite Chow's heroic act, 12 P-40s and one fleet trainer were destroyed on the ground. Chow received the Blue-Sky-White-Sun (Chinese Nationalist emblem) award personally from Chiang Kai-shek. By June 1943, the ground operations on the front of the "Rice Bowl" campaign were stabilized. In that campaign from 19 May to 6 June 1943, the Chinese Air Force flew on 336 fighter sorties and 88 bombing missions. The "Rice Bowl" campaign took its toll on the Chinese Air Force, which suffered heavy losses in combat and on the ground. At the end of the campaign the Chinese Air Force units numbered no more than a total of 77 combat aircraft, including seven A-29s, ten SBs, five P-40Es, nine P-43s and 46 P-66s, and of the total only 59 were serviceable. In May, the 14th Air Force received about 50 new P-40K, P-40M and P-40A fighters, and high-altitude Lockheed P-38 Lightning fighters in July, phasing out the old P-40s. From July to September 1943, Japanese air units carried out concentrated attacks