Military occupation is a question of fact.
11.2.1 The fact of occupation is the basis for the Occupying Power to exercise authority over the occupied territory. The fact of occupation, as a requirement for the exercise of authority over the occupied territory, prevents a State from simply claiming the authorities of military government over an enemy territory without actually controlling such territory.
'''11.2.2 Standard for Determining When Territory Is Considered Occupied. Territory is
considered occupied when it is actually placed under the authority of the hostile forces.'''
This standard for when the law of belligerent occupation applies is reflected in Article 42
of the Hague IV Regulations and is regarded as customary international law.
11.2.2.1 “Actually Placed” – Effectiveness of Occupation. Military occupation must be actual and effective; that is, the organized resistance must have been overcome, and the Occupying Power must have taken measures to establish its authority.
'''It is sufficient that the occupying force can, within a reasonable time, send detachments
of forces to enforce its authority within the occupied district.''' Military occupation does not require the presence of military forces in every populated area, although the occupying force must, inter alia, control the most important places.
[Note: There is no legal requirement that the national guard members involved in the occupation have to even know why are there, and it's ok if they want to lay down and fall asleep wherever they want.]
https://dod.defense.gov/Portals/1/Documents/pubs/DoD%20Law%20of%20War%20Manual%20-%20June%202015%20Updated%20Dec%202016.pdf?ver=2016-12-13-172036-190