 Complete the following phrase:  Intruding French and British formations became larger, more elaborate, harder for JG II to combat. Fresh new American air units began to appear. The Allies launched their final offensive on 8 August, including a huge effort by the Royal Air Force. On 10 August, Berthold scored the last of his 16 victories for the wing, and was then shot down and hospitalized. After his departure, the wings supplies continued to decline and experienced aces were falling while replacements were scarce. By 12 September, the balance of power had so shifted that the Imperial German Air Service could only muster about 70 fighters at 