Final answer:
The Executive Government of the United States, particularly its military and naval forces, were responsible for enforcing the Emancipation Proclamation.
Step-by-step explanation:
The entity responsible for enforcing the Emancipation Proclamation's directives is identified within the document itself. It explicitly mentions that the Executive Government of the United States, including the military and naval authority thereof, will recognize and maintain the freedom of those persons formerly held as slaves. Therefore, it is the Soldiers and sailors of the United States who, under the guidance and orders of the Executive branch, are given the duty to uphold the terms of the proclamation, particularly in areas in rebellion against the United States where the proclamation applies.