Gutenkunst Phil.  bm.  In May 1861, after President Abraham Lincoln called for volunteer troops, Rush requested to be a brigadier general in charge of Pennsylvania Volunteer artillery forces but the request was not approved by Pennsylvania Governor Andrew Gregg Curtin. Rush was granted permission by the Governor to muster a cavalry regiment, the Philadelphia Light Cavalry,[4] the 70th Regiment of Pennsylvania Volunteers, known also as "Rush's Lancers".[5] The regiment consisted of many recruits from Rush's Germantown neighborhood in Philadelphia and the officers were Rush's personal friends.[3] Rush was promoted to colonel on July 27, 1861, and the regiment was incorporated into the Army of the Potomac on October 5, 1861,[7] as the 6th Pennsylvania Cavalry Regiment.[5]The regiment entered Virginia on March 10, 1862, and was attached to the Second Brigade, Cavalry Reserve led by William H. Emory.[8] The regiment fought well at the Battle of Hanover Court House, capturing prisoners and serving as scouts and couriers. However, the unit was routed and driven from the field at the Battle of Gaines' Mill.[9] During the Maryland campaign, he led the third brigade of the cavalry division under brigadier general Alfred Pleasonton.[10] He received battle honors for service at the Battle of Hanover Court House, the Battle of Gaines' Mill, the Battle of White Oak Swamp, the Battle of South Mountain,[11] and the Battle of Antietam.[7][12] He took sick leave from the regiment on April 25, 1863, due to a relapse of malaria contracted during the Mexican-American War.[4] Temporary command of the regiment was given to Robert Murray Morris. Despite being on sick leave, Rush was officially listed as colonel for the regiment until September 29, 1863, when command was given to Charles L. Leiper.[8]Rush was seconded to the Provost Marshal General's Bureau from 10 May – 10 November 1863.[6] He helped organize the Veteran Reserve Corps and served at Rock Island Prison from November 10 – December, 20 1863.[7] He served as President of a Board for Examination of Officers from January 3 – March 20, 1864. He resigned from the Army on July 1, 1864.[5][6]He died on October 17, 1893,[1] in Philadelphia of heart failure[13] and was interred at Laurel Hill Cemetery