Squadrons were sent to Kunming on 18 December, guarding Kunming and the Chinese section of the Burma Road against Japanese air attacks. On 20 December, the Flying Tigers saw their first action in the skies of Kunming when the 1st and 2nd Squadrons intercepted a formation of Japanese planes on a bombing raid; the Flying Tigers shot down nine of ten Japanese bombers and lost one P-40. Three days later, the Flying Tigers' 3rd Squadron inflicted comparable damage on a formation of Japanese planes on a bombing raid to Rangoon. For the next six months, the aerial battles of the Flying Tigers' P-40s with Japanese fighter and bomber aircraft were regular sights in the skies over south Yunnan and Burma. When Rangoon fell to Japanese forces in early March 1942, Chennault withdrew all Flying Tigers squadrons to the Wujiaba airbase in Kunming. The Japanese fighter aircraft were more maneuverable as compared to the Flying Tigers's P-40. However, the Flying Tigers' pilots were able to take advantage of the fast diving speed and heavy firepower of their P-40s in "boom and zoom" (hit and run) tactics to gain an advantage over the agile but armorless Japanese fighters. The American Volunteer Group was officially disbanded on 4 July 1942 when its one-year contract expired. The Group celebrated its final day by shooting down five Japanese fighters over Hengyang and escorting B-25 bombers of the United States Army Air Forces to bomb the Japanese air base at Guangzhou. In the short period of some six months from 20 December 1941 to the beginning of July 1942, the Flying Tigers had flown on more than 50 combat missions, destroying 299 Japanese planes including bombers, Nakajima Ki-43 fighters, and 153 probables; the Flying Tigers lost 12 planes in air battles and 61 on the ground; 13 pilots were killed and three were captured as prisoners of war. Those were incredible records in aerial combat. However, the Japanese immediate voiced their discontent with the American tactics through their English-language propaganda broadcasts by Tokyo Rose, who called the Americans "cowards", and continuously challenged the American pilots to "stop running away" (to the general amusement of the American pilots who tuned in to her broadcasts). 1942 After the attack on Pearl Harbor, with the top-units of the Japanese Army and Navy air forces dispatched to the Pacific War theater, the Chinese Air Force was in preparation for transition