Complex sentence: On July 7, Companies "C" and "F" were ordered to Weston, Missouri, and during July, August, and a portion of September, they remained on active duty and succeeded in clearing the counties of guerrillas.
Split into simpler sentences: On July 7, Companies "C" and "F" were ordered to Weston, Missouri, and operated from there in driving the guerrillas from this territory. During July, August, and a portion of September, they remained on active duty and succeeded in clearing the counties of guerrillas.