Detachment (Old Frenchde, from, and[at]tach, joining with a stake) underinternational law is theformal, permanent separation of and loss ofsovereignty over some territory to another geopolitical entity (either adjacent or noncontiguous). Detachment can be considered the opposite or reverse ofannexation.
A prominent example of detachment is the official and formal relinquishment ofAlsace andLorraine byGermany, followingWorld War I. More often, however, detachment is a result of the creation of a new,sub-national geographical entity within one country. When detachment occurs within a country, the new entity is usually administered subsequently by a supervening entity,[1][2] such as a national/federal government. For example, after theUnited States became independent in 1776, it was considered desirable, for various reasons, for thefederal capital to be situated beyond the boundaries and jurisdiction of the constituentStates. Consequently, in 1790, the States ofMaryland andVirginia agreed to permanently detach adjoining areas on their border, to become theDistrict of Columbia (DC), including the site of the future city ofWashington DC. The formal removal of a smaller area from a city, town, or incorporated, non-urban district is also considered to be a form of detachment.[1][3] For example, while the city ofAlexandria, Virginia and the neighboringAlexandria County were detached from Virginia, to become a founding parts of the District of Columbia, the residents of Alexandria and Alexandria County (later Arlington County) began to campaign for the area's "retrocession" (or reattachment) to Virginia. Thisoccurred in 1847.
The formal detachment of Egypt from the Ottoman Empire was a condition for British investment in theSuez Canal.[4]
After World War I, a number of colonial territories and border territories were detached from theGerman Empire as well as portions of theAustrian-Hungarian Empire and theOttoman Empire. Some of the detachments were incorporated directly into new countries, such asYugoslavia, or annexed by existing countries such asNorthern Schleswig intoDenmark. Some, however, particularly in theMiddle East and those of theGerman colonies, were placed under the "protection" of one or another of theAllied countries that had won the war, including Germany's concessions inChina,Kiautschou andChefoo. From arule of law standpoint, theprotectorates were not warbooty but "mandates" from a legally-constituted international body and so detachment occurred without annexation.[5]