Detachment may mean:
Detachment (Old French de, from, and [at]tach, joining with a stake) under international law is the formal, permanent separation of and loss of sovereignty over some territory to another geo-political entity (either adjacent or non-contiguous). After World War I Alsace and Lorraine were a formal detachment from Germany. More often detachment occurs as a process within a country, for example the creation of the Federal District of Columbia resulted from a detachment of territory from the State of Maryland. The removal of territory from a city or special district is a detachment. Within a country detachment is governed by the laws of the supervening entity. Detachment can be considered the opposite or reverse of annexation.
The formal detachment of Egypt from the Turkish Empire was a condition for British investment in the Suez Canal.
Following World War I, a number of colonial territories and border territories were detached from Germany, as well as portions of the Austrian-Hungarian Empire and Ottoman Empire being detached. Some of these detachments were incorporated directly into new countries, such as Yugoslavia, or annexed by existing countries such as Northern Schleswig into Denmark. But some, particularly in the Middle East and those of the German colonies, were placed under the "protection" of one or another of the Allied countries who won the war, including Germany's concessions in China, Kiautschou and Chefoo. From a rule of law standpoint these protectorates were not war booty, but "mandates" from a legally constituted international body, so detachment occurred without annexation.
A detachment (from the French détachement) is a military unit. It can either be detached from a larger unit for a specific function or (particularly in United States Military usage) be a permanent unit smaller than a battalion. The term is often used to refer to a unit that is assigned to a different base from the parent unit.
An example is the United States Army's 1st Special Forces Operational Detachment-Delta (Airborne) (1st SFOD-D (A)), commonly known as Delta Force by the general public.
Detachment is also the term used as the collective noun for personnel manning an artillery piece (e.g. gun detachment).
The Army Cadet Force in the United Kingdom breaks its structure down into local detachments which usually consist of between 10 and 40 cadets. Several detachments make up a company.
The Combined Cadet Force, however, does not use this term. Individual units are known as Cadet Contingents.