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