While the wartime capital of China was pushed back to Chongqing following the Fall of Wuhan, both sea and land routes for badly needed war supplies and high-octane aviation fuel were mostly cut-off, especially after the loss of Nanning in the Battle of South Guangxi and increasing threat of the Japanese invasion of French Indochina, Major Louie Yim-qun's 28th Fighter Squadron, now equipped with Polikarpov I-15 fighters, has been reassigned with the defense of Sichuan. On 13 September 1940, in what would be the introduction and first aerial combat engagement for the state-of-the-art new A6M "Zero" fighter, Maj. Louie led six I-15bis to join a formation 19 I-15bis and nine I-16s commanded by Major Cheng Hsiao-yu, Captain Yang Meng-ging and Captain Zhang Hong; they were engaged in a 1/2-hour long dogfight with 13 Zero fighters led by Lieutenant Saburo Shindo of the 12th Kokutai on an escort mission for 27 G3M "Nell" medium-heavy bombers on a raid against Chongqing. In the ensuing melee, Maj. Louie was seriously wounded, but managed to safely land his bullet-riddled I-15bis back in base, while Lt. Gao Youxin claimed a "Zero shot down", but in fact all Zeroes safely returned to base with 4 Zeroes suffering from some damage.