Complex sentence: With the Meuse-Argonne offensive starting on 26 September, more bomber escort missions were undertaken though the end of the month, and combat missions were undertaken throughout October supporting the offensive with bombing and escort missions over enemy territory, supporting First Army.
Split into simpler sentences: With the Meuse-Argonne offensive starting on 26 September, more bomber escort missions were undertaken though the end of the month. Combat missions were undertaken throughout October supporting the offensive with bombing and escort missions over enemy territory in support of First Army.