Department of Pennsylvania

The Department of Pennsylvania was a Union Military Department constituted on April 27, 1861 to consist of Pennsylvania, Delaware, and all of Maryland not embraced in the Department of Annapolis or the Department of Washington. It was merged into the Department of the Potomac on August 24, 1861 and recreated on December 1, 1864 from the Department of the Susquehanna..
On April 27, 1861, Adjutant-General Lorenzo Thomas issued General Orders Number 12 constituting the Department of Pennsylvania. Major General Robert Patterson assumed command of the Department at Philadelphia, Pennsylvania on April 29. he was succeeded by Major General John A. Dix at Baltimore on July 25. 
== Statistical Information ==
* Begin: April 27, 1861
* End: August 24, 1861 (Merged into Department of the Potomac)
* Recreated: December 1, 1864 (Changed from Department of the Susquehanna)
== Roster of Units ==
=== 1st Organization ===
COMMANDERS
* April 29, 1861 - July 25, 1861: Robert Patterson (Major General)
* July 25, 1861 - August 24, 1861: John A. Dix (Major General)
Divisions 	Brigades 	Regiments or Smaller Units 	Dates of Service 	Previous Unit 	Next Unit
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	 	 	 	 	
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	 	 	 	
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	6th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	17th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	21st Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	(I) 23rd Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	2nd United States Cavalry 	June 1861 - July 1861	Garrison at Carlisle Barracks, Pennsylvania 	(I) Dept. of the Shenandoah / 1st Brig.
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	1st Brigade George H. Thomas (Colonel, 2nd United States Cavalry) 	1st Rhode Island Light Artillery Battery 	June 1861 - July 1861	Department of Northeastern Virginia / Hunter's Division	(I) Dept. of the Shenandoah / 1st Brig.
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	3rd BrigadeA.S. Williams (Brigadier General) 	 	 	 	
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	3rd BrigadeA.S. Williams (Brigadier General) 	7th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	3rd BrigadeA.S. Williams (Brigadier General) 	8th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	3rd BrigadeA.S. Williams (Brigadier General) 	10th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	3rd BrigadeA.S. Williams (Brigadier General) 	12th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	 	 	 	
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	9th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	13th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	16th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	2nd United States Regular InfantryListed in this unit on ACWR 270, but this part of the unit history does not appear on ACWR 1710.	June 1861 - July 1861	From Regular Army garrison 	To Defences of Washington
1ST DIVISIONApril 27, 1861 - July 25, 1861:George Cadwaller (Brigadier General)July 25, 1861 - August 24, 1861:John A. Dix (Major General)	4th Brigade April 27, 1861 - July 2, 1861:J.C. Longenecker (Colonel, U.S. Army)July 2, 1861 - July 5, 1861:D.S. Miles (?)	3rd United States Regular InfantryListed in this unit on ACWR 270, but this part of the unit history does not appear on ACWR 1710.	June 1861 - July 1861	From Regular Army garrison 	To Defences of Washington
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	 	 	 	 	
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	2nd BrigadeApril 27, 1861 - July 25, 1861:George C. Wynkoop (Brigadier General) 	 	 	 	
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	2nd BrigadeApril 27, 1861 - July 25, 1861:George C. Wynkoop (Brigadier General) 	1st Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	2nd BrigadeApril 27, 1861 - July 25, 1861:George C. Wynkoop (Brigadier General) 	2nd Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	(I) Dept. of the Shenandoah / 1st Brig.ACWR 0270 says this unit mustered out and the unit history on ACWR 1577 does not mention this unit changing. Howwever, it is listed on ACWR 0272 under (I) Dept. of the Shenandoah / 1st Brig.. For now, it has been left this way.
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	2nd BrigadeApril 27, 1861 - July 25, 1861:George C. Wynkoop (Brigadier General) 	3rd Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	2nd BrigadeApril 27, 1861 - July 25, 1861:George C. Wynkoop (Brigadier General) 	24th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	5th Brigade (Negley)
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	5th BrigadeJ.S. Negley (Brigadier General) 	 	 	 	
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	5th BrigadeJ.S. Negley (Brigadier General) 	14th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	5th BrigadeJ.S. Negley (Brigadier General) 	15th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	5th BrigadeJ.S. Negley (Brigadier General) 	24th Pennsylvania Infantry 	June 1861 - July 1861	4th Brigade (Wynkoop) 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	6th BrigadeJ.J. Abercrombie (Brigadier General) 	 	 	 	
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	6th BrigadeJ.J. Abercrombie (Brigadier General) 	(I) 11th Pennsylvania Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	6th BrigadeJ.J. Abercrombie (Brigadier General) 	(I) 1st Wisconsin Infantry 	June 1861 - July 1861	From new organization 	No change to muster out
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	6th BrigadeJ.J. Abercrombie (Brigadier General) 	4th Connecticut Infantry 	June 1861 - July 1861	From new organization 	(I) Dept. of the Shenandoah / 2nd Brig.
2ND DIVISIONApril 27, 1861 - July 25, 1861:W.H. Keim (Major General) 	6th BrigadeJ.J. Abercrombie (Brigadier General) 	2nd Massachusetts Infantry 	June 1861 - July 1861	From new organization 	(I) Dept. of the Shenandoah / 2nd Brig.
3RD DIVISIONC.P. Sanford (Major General) 	 	 	 	 	
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	 	 	 	
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	1st New Hampshire Infantry 	July 1861 - July 1861	From Stone's Rockville Expedition 	(I) Dept. of the Shenandoah / 3rd Brig.
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	83rd New York Infantry 	July 1861 - July 1861	From Stone's Rockville Expedition 	(I) Dept. of the Shenandoah / 3rd Brig.
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	25th Pennsylvania Infantry 	July 1861 - July 1861	From Stone's Rockville Expedition 	No change to muster out
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	District of Columbia Volunteers 	July 1861 - July 1861	From Stone's Rockville Expedition 	To Defences of Washington
3RD DIVISIONC.P. Sanford (Major General) 	7th BrigadeC.P. Stone (Colonel, U.S. Army) 	4th United States Artillery / Battery F 	July 1861 - July 1861	From Carlisle, Pennsylvania 	(I) Dept. of the Shenandoah / 3rd Brig.
3RD DIVISIONC.P. Sanford (Major General) 	8th BrigadeDaniel Butterfield (Colonel, 12th New York Infantry) 	 	 	 	
3RD DIVISIONC.P. Sanford (Major General) 	8th BrigadeDaniel Butterfield (Colonel, 12th New York Infantry) 	(I) 5th New York Infantry 	July 1861 - July 1861	Department of Northeastern Virginia / Washington, D.C. 	No change to muster out
3RD DIVISIONC.P. Sanford (Major General) 	8th BrigadeDaniel Butterfield (Colonel, 12th New York Infantry) 	(I) 12th New York Infantry 	July 1861 - July 1861	Department of Northeastern Virginia / Washington, D.C. 	No change to muster out
3RD DIVISIONC.P. Sanford (Major General) 	8th BrigadeDaniel Butterfield (Colonel, 12th New York Infantry) 	19th New York Infantry 	July 1861 - July 1861	Department of Northeastern Virginia / Washington, D.C. 	(I) Dept. of the Shenandoah / 1st Brig.
3RD DIVISIONC.P. Sanford (Major General) 	8th BrigadeDaniel Butterfield (Colonel, 12th New York Infantry) 	(I) 28th New York Infantry 	July 1861 - July 1861	Department of Northeastern Virginia / Washington, D.C. 	(I) Dept. of the Shenandoah / 1st Brig.
Unassigned 	Unassigned 	 	 	 	
Unassigned 	Unassigned 	(I) 11th Indiana Infantry 	July 1961 - July 1861	From Cumberland, Maryland 	No change to muster out
=== 2nd Organization ===
COMMANDERS
* December 1, 1864 - June 27, 1865 : George Cadwallader (Major General)
== Notes ==
== Sources ==
* (Page 607)
* (Page 270)
* https://catalog.archives.gov/id/10511415
* https://www.nytimes.com/1861/05/02/archives/important-war-department-order-general-orders-no-12.html
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