Complex sentence: The commanding officer of the regiment, Col. Edward Winslow Hinks, respecting Devereux's expertise in military drill, placed the training of the 19th Massachusetts under Devereux's supervision.
Split into simpler sentences: The commanding officer of the regiment, Col. Edward Winslow Hinks had great respect for Devereux's expertise in military drill. He therefore placed the training of the 19th Massachusetts under Devereux's supervision.