Robert Patterson Robert Patterson ( January 20 , 1792 – August 7 , 1881 ) was a United States major general during the Mexican - American War and the American Civil War . During the onset of the latter , he commanded a brief engagement with Colonel Thomas J . Jackson on July 2 , 1861 , at the Battle of Hoke ' s Run and produced an early Union victory . His inability to contain a smaller Confederate army under General Joseph E . Johnston within the Shenandoah Valley was a proximate cause for the Union Army ' s defeat at the First Battle of Bull Run , but among Johnston ' s stated reasons for avoiding pursuit of the shattered Union Army as it fled in retreat to Washington , the size , integrity and mobility of Patterson ' s Army is prominent . Shortly after First Bull Run , the three - month term of the volunteers who comprised a majority of his army expired , Patterson was honorably discharged with them , and his active military career ended . Early life and War of 1812 . Patterson was born in Cappagh , County Tyrone , Ireland . His family was banished from Ireland due to his father ' s involvement as an insurrectionist . In 1799 he emigrated to the United States , where he eventually became involved in banking at a young age . Patterson received his education in public schools and afterward became a clerk in a Philadelphia counting house . He volunteered for service during the War of 1812 and rose from captain to colonel in the 2nd Pennsylvania Militia before joining the United States Army . He served in the Quartermaster General Department and was discharged in 1815 as a captain . After the war , he became influential in politics in Pennsylvania . Mexican - American War service . Patterson was commissioned a major general of volunteers at the outbreak of the Mexican - American War and commanded the 2nd Division , Army of Occupation , during the Tampico Expedition . He was considered for command of the expedition to Veracruz which eventually went to Winfield Scott . He was , however , placed in command of the expedition ' s Volunteer Division and saw action during the Siege of Veracruz and at the Battle of Cerro Gordo , where he was wounded . He led the American pursuit of the Mexican Army and was the first to enter Jalapa . While the U . S . Army was stationed at Jalapa , Patterson returned to the U . S . with other volunteer units whose enlistment time had expired . He then resumed his business interests in Pennsylvania , where he acquired 30 cotton mills and became quite wealthy . He again was an influential figure in Philadelphia politics . Civil War service . The American Civil War brought Patterson back to military service . He was appointed major general of Pennsylvania volunteers and commanded the Department of Pennsylvania and the Army of the Shenandoah . In 1861 , Winfield Scott , now General - in - Chief of the U . S . Army , gave Patterson vague orders to retake Harpers Ferry . Patterson failed to immediately act on these orders , was outmaneuvered after the Battle of Hoke ' s Run , and a Confederate army at Winchester , Virginia , under Brig . Gen . Joseph E . Johnston , was able to march without interference to reinforce the Confederates at the First Battle of Bull Run . Patterson , widely criticized for his failure to contain the enemy forces , was mustered out of the Army in late July 1861 . Postbellum life . Patterson again returned to his cotton milling business and wrote a book , " A Narrative of the Campaign in the Valley of the Shenandoah , in 1861 " , published in 1865 . He was also President of the Aztec Club of 1847 from 1867 to 1881 and was a Companion of the Military Order of the Loyal Legion of the United States . Patterson died in Philadelphia and is buried there in Laurel Hill Cemetery . His son Francis Engle Patterson and his son - in - law John Joseph Abercrombie were both Union generals during the American Civil War .