* The army of a specific king: For example, "King Henry VIII's army" or "King Louis XIV's army".
* A generic term for a king's military: This would simply refer to any army that is led by a king.
To give you a more accurate answer, please tell me:
* Which king are you asking about?
* What time period are you interested in?
* What specific information are you looking for?
Once you provide me with this information, I can give you a more relevant answer.