Original sentence: 5 that they were able to compete successfully for control of the air.The early aircraft of the RFC were inferior to their German rivals in April 1917, (Bloody April) the RFC lost over 300 aircrew and 245 aircraft
Edited sentence: 5, that they were able to compete successfully for control of the air.The early aircraft of the RFC were inferior to their German rivals; in April 1917, (Bloody April) the RFC lost over 300 aircrew and 245 aircraft