The "Maryland Line" was a formation within the Continental Army, formed and authorized by the Second Continental Congress, meeting in the "Old Pennsylvania State House" (later known as "Independence Hall") in Philadelphia, Pennsylvania in June 1775, and authority given to Col. George Washington, delegate and formerly of the "Virginia Regiment" of the colonial militia to serve as commander-in-chief of the colonial forces and he assumed command at Cambridge, Massachusetts outside of Boston, of the various units from several of the American colonies surrounding Boston, laying siege to the British Army within, in June 1775. His previous military experience had been during the late French and Indian War (1754–1763), [also known as the Seven Years' War in Europe]. The term "Maryland Line" referred to the quota of numbered infantry regiments assigned to Maryland at various times by the Continental Congress. These, together with similar contingents from the other twelve states, formed the "Continental Line". The concept was particularly important in relation to the promotion of commissioned officers. Officers of the Continental Army below the rank of brigadier general were ordinarily ineligible for promotion except in the line of their own state.
Not all Continental infantry regiments raised in a state were part of a state quota, however. On December 27, 1776, the Second Continental Congress gave commanding General George Washington temporary control over certain military decisions that the Congress ordinarily regarded as its own prerogative. These “dictatorial powers” included the authority to recruit and raise sixteen additional Continental infantry regiments at large.
Forman’s, Gist’s, Grayson’s, and Hartley’s Regiments were partially drawn from Maryland.
Still other Continental infantry regiments and smaller units, also unrelated to a state quota, were raised as needed for special or temporary service.
The "Maryland Line" has a reputation of being among the best of the Continental Army. Because of the long service of the high quality regiments, General Washington, according to tradition, referred to the Maryland units as his "Old Line", giving the State of Maryland one of its nicknames as "The Old Line State".
The "Maryland Line" was assigned a quota of eight regiments in 1777, which was reduced to five in 1781. The regiments of the line were:
- 1st Maryland Regiment, disbanded in 1783
- 2nd Maryland Regiment, disbanded in 1783
- 3rd Maryland Regiment, disbanded in 1783
- 4th Maryland Regiment, disbanded in 1783
- 5th Maryland Regiment, disbanded in 1783
- 6th Maryland Regiment, disbanded in 1781
- 7th Maryland Regiment, disbanded in 1781
- German Battalion (counted as half a regiment against the quota), disbanded in 1781
- Maryland and Virginia Rifle Regiment (counted as half a regiment against the quota), disbanded in 1781
- 2nd Independent Maryland Company - Somerset County absorbed into the 2nd Maryland Regiment in 1781
- Wright, "ontinental Army, 322–323.
- State Nicknames
- Polk, Ryan. - "Holding the Line: The Origin of the 'the Old Line State']". Maryland State Archives, Annapolis, 2005. Available on internet website: 
- Wright, Robert K. - "The Continental Army", Washington, D.C.: United States Army Center of Military History, 1983. Available on internet website: online.
- "Bibliography of the Continental Army in Maryland", Washington, D.C.: compiled by the United States Army Center of Military History. Available on internet website: