Departments of the Continental Army 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 . This was necessary because the regiment was the largest permanent unit in the Continental Army . A superior headquarters , above regiment , was needed if more than a few regiments were stationed in the same department . Although brigade s , divisions , and field armies existed , they were temporary units which did not necessarily include all the units assigned to a department . Nor did field armies include establishments of the staff , such as " magazines " ( supply depots ) of the Quartermaster General ' s Department , or hospitals of the Hospital Department . The militia in a department was usually at the disposal of the department commander . Departmental organization . The Continental troops in a department constituted its garrison . If the garrison was sufficiently large , the units might be assembled into a field army . In this case the commander of the territorial department and the commander of the field army would be one and the same officer . Thus , the commanding general of the Northern Department was also commanding general of the Northern Army , and the commanding general of the Southern Department was also commanding general of the Southern Army . Armies did not , however , invariably receive a geographical designation . Because the field army under Washington ' s personal command contained the majority of Continental Army units it was , for obvious reasons , designated the Main Army . Each department had a semi - autonomous commanding officer , usually a commanding general , under the overall command of Washington as General and Commander - in - Chief . The Continental Congress dealt with and through the department commanders . Appointment of department commanders . 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 . Many of these temporary department commanders were then confirmed and formally appointed by the 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 . Relations between the departments and the states . The department commanders and their staffs also worked directly with the governments of the states within their department . At first these were the " ad hoc " provisional governments developed in 1774 and 1775 , but the practice continued after 1776 when the states replaced their Provincial Congresses and Conventions with permanent governments operating under written constitutions . Ordinarily departments were commanded by major generals . Washington as a full general was the ranking general officer in the Continental Army throughout the war . Departments . In general there were seven territorial departments , although their boundaries were subject to change and they were not all in existence throughout the war . Canadian Department . 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 . The Canadian Department was formally established from the New York Department on January 17 , 1776 . After the Invasion of Canada failed , all troops were withdrawn to Fort Ticonderoga , New York . The Canadian Department was officially discontinued on July 8 , 1776 . Eastern Department . 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 . This was essentially the New England department , and included the states of New Hampshire , Massachusetts ( including the present state of Maine ) , Rhode Island , and Connecticut . For the first year of the war , the field army associated with this department , under the command of General Washington , was variously designated as the Continental Army , Grand Army , or Main Army . The Eastern Department was formally established on April 4 , 1776 when the Main Army under Washington moved from Boston to New York City . Important operations in this department included the Siege of Boston in 1775 – 1776 and the Battle of Rhode Island in 1779 . The department was discontinued in November 1779 . Northern Department . The predecessor of the Northern Department was the New York Department , which was established on June 25 , 1775 . This department was sometimes described as the Separate Department and the troops stationed in it were known as the " Separate Army " . The original New York Department was coextensive with the Province of New York . The department ' s boundaries were extended to include Canada in the initial phase of the Invasion of Canada , but Canada was established as a separate department on January 17 , 1776 . When the Middle Department was created on February 27 , 1776 the New York Department was merged into it . The Middle Department , as originally organized , included all of the colonies of New York , New Jersey , Pennsylvania , Delaware , and Maryland . The inclusion of New York in the Middle Department continued for less than two months , however . In April 1776 the Main Army moved from Boston to New York City and Washington assumed command of the Middle Department . The Northern Department was formally established from the Middle Department on April 14 , 1776 . 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 . The field army associated with the Northern Department was known as the Northern Army . Operations in this department did not end with Saratoga . Fighting continued in the Northern Department until the end of the war . The department was discontinued upon the death of its last commander , General Alexander , at Albany on January 15 , 1783 . Highlands Department . The Highlands Department was the smallest in area . Strictly speaking , it was part of the Middle Department , but because of its importance it was virtually a separate department . The Highlands Department was formed around the defenses on the Hudson River about north of New York City , where the Appalachians and the Hudson intersect . After the British occupied New York City in 1776 the defenses just north of there became critically important . The presence of British naval forces at New York emphasized the importance of the Hudson River , and both sides in the war recognized the importance of controlling that waterway . The Americans created fortifications , including West Point with its chain across the river . Washington assigned Continental troops under General Heath to the Highlands on November 12 , 1776 and there was a Continental Army garrison in the Highlands from then until the end of the war . Heath ' s assignment thus created a " de facto " military department . 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 . One of the most notable incidents in the history of this department was the defection of Benedict Arnold in September 1780 . Middle Department . The Middle Department was established on February 27 , 1776 . Originally it 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 , and became the field army associated with the Middle Department for the remainder of the war . On April 14 , 1776 that portion of New York north of the Hudson Highlands , and the present state of Vermont were separated from the Middle Department and organized as the Northern Department . The Middle Department then comprised the Hudson Highlands in the state of New York , the rest of New York south of the Highlands , and the states of New Jersey , Pennsylvania , Delaware , and Maryland . The term Main Army had come into use during the Siege of Boston , because the majority of Continental Army regiments were assigned to it . The term was retained throughout the war . Most units in the Middle Department were assigned to the Main Army , under George Washington , or to the Highlands Department , which was under Washington ' s close supervision . A few regiments and independent companies were assigned to the Middle Department from time to time , but were not assigned to Washington ' s army or to the Highlands . These units were simply said to have been assigned to the Middle Department . Some of the Continental Army ' s most important campaigns were fought in this department . These included the New York campaign and the New Jersey campaign which ended with the battles of Trenton and Princeton . The Philadelphia campaign was fought in this department , after which the Continental Army went into winter quarters at Valley Forge . In 1778 this department was the scene of the Monmouth campaign . After Monmouth , on June 28 , 1778 , major military operations in the United States shifted to the Southern Department . The department existed until the close of the war . It was the scene of one of the war ' s last episodes when the British Army evacuated New York City on November 25 , 1783 . Western 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 . It extended from Pittsburgh all the way to the Illinois country and as far north as the southern peninsula of Michigan . The department was established in 1777 . Its first commander was Edward Hand . George Rogers Clark ' s Illinois campaign of 1779 was one of the most notable operations in this department . This department was the only one to remain after the war . The last elements of the Continental Army , stationed at Fort Pitt , were kept to guard the western frontier outposts . Southern Department . The Southern Department was formally established on February 27 , 1776 . The department included Virginia , North Carolina , South Carolina , and Georgia and the western frontiers of those colonies , from which were created the present states of West Virginia , Kentucky , Tennessee , Alabama , and Mississippi . The field army associated with this department was known as the Southern Army . The Southern Department was the most independent of the commands due to geography and the need for year round operations . Most of the territorial departments to the north of this department suspended offensive operations for the winter and early spring . The Southern Department was also the only one in which the troops assigned were destroyed twice . The first time was at the surrender of Charleston on May 12 , 1780 . The second was at the Battle of Camden on August 16 , 1780 . 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 . The Southern Department existed until the close of the war . online .