Final answer:
Sub-unified and JTF commanders exercise control to ensure order and meet strategic goals, including the establishment of governance and oversight of constitutional drafting during periods like Reconstruction, and to achieve objectives in military operations.
Step-by-step explanation:
The purpose of Sub-unified commanders and JTF (Joint Task Force) commanders exercising control over military districts or operations is to maintain order, oversee the establishment of governance, and to ensure that strategic objectives are met. For instance, during the period of Reconstruction after the American Civil War, military districts were set up under the command of federal military commanders. Their responsibilities included setting new voting requirements, establishing new state governments, and overseeing the drafting of state constitutions. In a more contemporary sense, JTF commanders coordinate military efforts to achieve specific goals during an operation, whether in combat or other strategic objectives.
In a broad militaristic context, mentioned in historical texts like Sun Tzu's "The Art of War", the lack of a unified command or the insubordination of higher officers can lead to disaster in an engagement with the enemy. Harmonized command ensures coherent strategy and disciplined action in military operations.