In the American Revolutionary War units of the Continental Army were assigned to any one of seven regional or territorial departments to decentralize their command and administration.
Throughout the war, the Continental Congress retained exclusive authority to appoint or remove department commanders.
In practice, when an urgent need arose, a temporary commander was just as frequently appointed by George Washington or the executive power of one of the states, pending the approval of the Continental Congress.
This practice, along with control of the Continental Army and Navy through the war and marine committees of the Continental Congress, established the precedent for civil control of military affairs later embodied in the Articles of Confederation and the United States Constitution.
The establishment of the Canadian Department reflected the aspirations of the Continental Congress and some Americans to annex the British province of Quebec, then often referred to as "Canada", but the effort was ultimately unsuccessful.
Although the Americans captured Montreal in November 1775, and established their headquarters at Château Ramezay, the region was never entirely under the control of the Continental Army.
[4] The Eastern Department was formed around those states that had originally sent troops to support the Siege of Boston, and in that sense it even existed before the Continental Army.
The Eastern Department was formally established on April 4, 1776[6] when the Main Army under Washington moved from Boston to New York City.
The Middle Department, as originally organized, included all of the colonies of New York, New Jersey, Pennsylvania, Delaware, and Maryland.
In April 1776 the Main Army moved from Boston to New York City and Washington assumed command of the Middle Department.
[11] The reorganized Northern Department included only that portion of the colony of New York north of the Hudson Highlands, and the present state of Vermont.
[13] The British sought to gain control with the Saratoga campaign in 1777, and frequently raided into the southern reaches of the department to interfere with the movement of military goods and personnel.
The Philadelphia campaign was fought in this department, after which the Continental Army went into winter quarters at Valley Forge.
After Monmouth, on June 28, 1778, major military operations in the United States shifted to the Southern Department.
The Western Department covered the frontier territories west and northwest of Virginia and Pennsylvania, including the present states of Ohio, Indiana, Illinois, Michigan, and Wisconsin.
The last elements of the Continental Army, stationed at Fort Pitt, were kept to guard the western frontier outposts.
Despite these two catastrophic defeats, however, this department was the location of the Siege of Yorktown, in 1781, which effectively decided the outcome of the war.
Important events in the Southern Department after Yorktown were the evacuation of Savannah and Charleston in July and December 1782.