 The introduction of the advanced A5M "Claude" fighters into the Shanghai-Nanjing theater of operations, beginning on September 18, 1937, helped the Japanese achieve a certain level of air superiority.However the few experienced Chinese veteran pilots, even in their older and slower biplanes, proved more than able to hold their own against the sleek A5Ms in dogfights, and it also proved to be a battle of attrition against the Chinese Air Force.At the start of the battle, the local strength of the NRA was around five divisions, or about 70,000 troops, while local Japanese forces comprised about 6,300 marines.