Why did Colonel Shaw bring in Sergeant Mulcahy in the movie Glory?

In the movie "Glory," Colonel Shaw brings in Sergeant Mulcahy to help with the training and leadership of the 54th Massachusetts Infantry Regiment, which was made up of African American soldiers. Shaw recognizes Mulcahy's experience and skills as a soldier, believing that he can effectively assist in preparing the troops for battle. Additionally, Mulcahy's presence adds a layer of support and camaraderie, reinforcing the notion of unity within the regiment as they face both external battles and internal challenges regarding their identity and purpose.