TheDepartment of the Susquehanna was a military department created by theUnited States War Department during theGettysburg Campaign of theAmerican Civil War. Its goal was to protect the state capital and the southern portions of the commonwealth ofPennsylvania, and to deny theConfederate army passage across the vitalSusquehanna River.

On June 9, 1863,PresidentAbraham Lincoln, responding toRobert E. Lee's impending invasion ofMaryland and Pennsylvania, called for 100,000 volunteers from Pennsylvania,New York, andOhio to help repel the invasion, with only about 33,000 recruits answering his call.Secretary of WarEdwin M. Stanton ordered the creation of two military departments, the Departments of the Susequehanna andMonongahela, to organize thesemilitia and defend the state of Pennsylvania. The Department of the Susquehanna consisted of all troops east ofJohnstown and theLaurel Highlands, and it was initially headquartered atChambersburg. It was placed under the command ofMajor GeneralDarius N. Couch, who had formerly commandedII Corps,Army of the Potomac.

As the Confederates entered theCumberland Valley, Couch moved his headquarters toHarrisburg. Militia from New York andNew Jersey arrived in the capital to provide manpower while the newly raised Pennsylvania emergency militia drilled atCamp Curtin. New York troops serving under the Department of the Susquehanna were first engaged in a skirmish with Confederatecavalry underAlbert G. Jenkins atGreencastle on June 20, losing one man killed (considered the first casualty of the Gettysburg Campaign on Northern soil). The New Yorkers eventually retired to Harrisburg, allowing Jenkins to occupy Chambersburg.

Couch ordered that no Confederate unit was to be allowed to cross the Susquehanna River. He authorized the construction of earthworks and fortifications nearLemoyne to defend Harrisburg and its river bridges. He assignedWilliam F. "Baldy" Smith to defend the state capital. Couch designated hisaide-de-camp,MajorGranville O. Haller, as the sector commander to defendAdams andYork counties, with regional headquarters inGettysburg. Couch sent out three regiments of state emergency militia to Haller's assistance, with the 26th Pennsylvania Volunteer Militia (P.V.M.) sent to Gettysburg, the 20th P.V.M. to York County, and the 27th P.V.M. toColumbia to defend theColumbia-Wrightsville Bridge, a vital crossing over the Susquehanna.

On June 26, 1863, advancing Confederates underJubal Early andJohn Brown Gordon routed Haller's militia at Gettysburg and occupied the borough. Haller retired toYork, which surrendered on June 28, becoming the largest Northern town to fall during the Civil War. Prior to the Confederate occupation, Haller removed his troops toWrightsville, where in obedience to Couch's orders, Haller ordered thecovered bridge burned to prevent Confederate passage intoLancaster County.

The troops of the department assigned to General Smith took part in skirmishes against elements ofRichard S. Ewell's corps inCumberland County at Sporting Hill on June 30 and againstJ.E.B. Stuart atCarlisle on July 1. Couch dispatched Smith's men, along with many of Haller's, to helpGeorge G. Meade pursue Robert E. Lee's retreatingArmy of Northern Virginia. The Department of the Susquehanna remained operational following the conclusion of the campaign, although many of the militia were sent home.

With the threat repelled, Couch moved his headquarters back to Chambersburg, and the department played an administrative role the rest of the year, providing militia to help clean up theGettysburg Battlefield and assisting in the military preparations for the dedication of theGettysburg National Cemetery and Lincoln's visit, which resulted in theGettysburg Address.

In January 1864, Couch responded with troops to rumors that a band of disgruntled constituents planned to prevent the inauguration of Pennsylvania GovernorAndrew Curtin. In March, with rumors rife of yet another raid, Couch made preparations to again defend the state. However, it was not until late July when the Confederates again arrived in Pennsylvania, whenJohn McCausland raided and burned Chambersburg. Couch was again engaged in sending out 100-day volunteers, militia and Federal troops to repel the enemy. In September, the department dispatched troops to various locations to help oversee themilitary draft.

The following month, the department again responded to a threatened Confederate border raid.Philip H. Sheridan's subsequent victories in theValley Campaigns of 1864 finally removed any further threats. On April 6, 1864, theDepartment of the Monongahela was incorporated into the department.^[1] On December 1, 1864, the Department of the Susquehanna was renamed as theDepartment of Pennsylvania.^[2]

• Boatner III, Lt. Col. Mark Mayo,The Civil War Dictionary. New York: Van Rees Press, 1959.
• U.S. War Department,The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, 70 volumes in 4 series. Washington, D.C.:United States Government Printing Office, 1880–1901.

• History of Harrisburg, Pennsylvania
• Pennsylvania in the American Civil War
• Union army departments
• 1863 establishments in the United States