As the Confederates entered the Cumberland Valley, Couch moved his headquarters to Harrisburg. Militia from New York and New Jersey arrived in the capital to provide manpower while the newly raised Pennsylvania emergency militia drilled at Camp Curtin. New York troops serving under the Department of the Susquehanna were first engaged in a skirmish with Confederate cavalry under Albert G. Jenkins at Greencastle 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.