|Outline of War|
Military occupation is effective provisional control of a certain power over a territory which is not under the formal sovereignty of that entity, without the volition of the actual sovereign. The intended temporary nature of occupation, when no claim for permanent sovereignty is made by the occupying entity, distinguishes occupation from both colonialism or annexation.
Military occupation and the laws of war 
From the second half of the 18th century onwards, international law has come to distinguish between the military occupation of a country and territorial acquisition by invasion and annexation, the difference between the two being originally expounded upon by Emerich de Vattel in The Law of Nations (1758). The clear distinction has been recognized among the principles of international law since the end of the Napoleonic wars in the 19th century. These customary laws of belligerent occupation which evolved as part of the laws of war gave some protection to the population under the military occupation of a belligerent power.
The Hague Conventions of 1907 further clarified and supplemented these customary laws, specifically within "Laws and Customs of War on Land" (Hague IV); October 18, 1907: "Section III Military Authority over the territory of the hostile State." The first two articles of that section state:
- Art. 42.
- Territory is considered occupied when it is actually placed under the authority of the hostile army.
- The occupation extends only to the territory where such authority has been established and can be exercised.
- Art. 43.
- The authority of the legitimate power having in fact passed into the hands of the occupant, the latter shall take all the measures in his power to restore, and ensure, as far as possible, public order and safety, while respecting, unless absolutely prevented, the laws in force in the country.
In 1949 these laws governing belligerent occupation of an enemy state's territory were further extended by the adoption of the Fourth Geneva Convention (GCIV). Much of GCIV is relevant to protected persons in occupied territories and Section III: Occupied territories is a specific section covering the issue.
Article 6 restricts the length of time that most of GCIV applies:
- The present Convention shall apply from the outset of any conflict or occupation mentioned in Article 2.
- In the territory of Parties to the conflict, the application of the present Convention shall cease on the general close of military operations.
- In the case of occupied territory, the application of the present Convention shall cease one year after the general close of military operations; however, the Occupying Power shall be bound, for the duration of the occupation, to the extent that such Power exercises the functions of government in such territory, by the provisions of the following Articles of the present Convention: 1 to 12, 27, 29 to 34, 47, 49, 51, 52, 53, 59, 61 to 77, 143.
GCIV emphasised an important change in international law. The United Nations Charter (June 26, 1945) had prohibited war of aggression (See articles 1.1, 2.3, 2.4) and GCIV Article 47, the first paragraph in Section III: Occupied territories, restricted the territorial gains which could be made through war by stating:
- Protected persons who are in occupied territory shall not be deprived, in any case or in any manner whatsoever, of the benefits of the present Convention by any change introduced, as the result of the occupation of a territory, into the institutions or government of the said territory, nor by any agreement concluded between the authorities of the occupied territories and the Occupying Power, nor by any annexation by the latter of the whole or part of the occupied territory.
Article 49 prohibits the forced mass movement of people out of or into occupied state's territory:
- Individual or mass forcible transfers, as well as deportations of protected persons from occupied territory to the territory of the Occupying Power or to that of any other country, occupied or not, are prohibited, regardless of their motive. ... The Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies.
Protocol I (1977): "Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts" has additional articles which cover military occupation but many countries including the U.S. are not signatory to this additional protocol.
In the situation of a territorial cession as the result of war, the specification of a "receiving country" in the peace treaty merely means that the country in question is authorized by the international community to establish civil government in the territory. The military government of the principal occupying power will continue past the point in time when the peace treaty comes into force, until it is legally supplanted.
"Military government continues until legally supplanted" is the rule, as stated in Military Government and Martial Law, by William E. Birkhimer, 3rd edition 1914.
Examples of military occupations 
In most wars some territory is placed under the authority of the hostile army. Most military occupations end with the cessation of hostilities. In some cases the occupied territory is returned and in others the land remains under the control of the occupying power but usually not as militarily occupied territory. Sometimes the status of presences is disputed by a party to the situation.
See also 
- List of military occupations
- Rule of Law in Armed Conflicts Project (RULAC)
- Military government
- Nazi-occupied Europe
- Allied Occupation Zones in Germany
Further reading 
- Occupied territory - the legal issues, legal provisions regarding occupation of territory by hostile power and implications for people protected by IHL.
- David Kretzmer, Occupation of Justice: The Supreme Court of Israel and the Occupied Territories, State University of New York Press, April, 2002, trade paperback, 262 pages, ISBN 0-7914-5338-3; hardcover, July, 2002, ISBN 0-7914-5337-5
- Sander D. Dikker Hupkes, What Constitutes Occupation? Israel as the occupying power in the Gaza Strip after the Disengagement, Leiden: Jongbloed 2008, 110 pages, ISBN 978-90-70062-45-3 Openacces
- Belligerent Occupation
- The Law of Belligerent Occupation Michal N. Schmitt (regarding occupation of Iraq)
- Law of Belligerent Occupation, Judge Advocate General's School, United States Army
- A Roberts. Prolonged Military Occupation: The Israeli-Occupied Territories Since 1967 - Am. J. Int'l L., 1990, p. 47.
- Eyāl Benveniśtî. The international law of occupation. Princeton University Press, 2004. ISBN 0-691-12130-3, ISBN 978-0-691-12130-7, p. xvi
- Eran Halperin, Daniel Bar-Tal, Keren Sharvit, Nimrod Rosler and Amiram Raviv. Socio-psychological implications for an occupying society: The case of Israel. Journal of Peace Research 2010; 47; 59
- During civil wars, the districts occupied by rebels are considered to be foreign.Military Government and Martial Law LLMC, p. 21. 
- David M. Edelstein. Occupational Hazards: Why Military Occupations Succeed or Fail. Journal of Peace Research 2010; 47; 59
- Laws and Customs of War on Land" (Hague IV); October 18, 1907: "Section III Military Authority over the territory of the hostile State source The Avalon Project at the Yale Law School