90th Pennsylvania Infantry The 90th Pennsylvania Volunteer Infantry was a volunteer infantry regiment which served in the Union Army during the American Civil War . They wore a chassuer uniform . The uniform consisted of a dark blue habit veste with white trimming , baggy sky blue trousers , and a dark blue kepi . The buttons on the habit veste was unique to the 90th Pennsylvania . They were the only Union regiment in the entire war to have a specific button design . History . The regiment was formed from the 2nd Regiment , 1st Brigade , First Division of the Pennsylvania Militia . Peter Lyle was selected colonel , William A . Leech lieutenant colonel and Alfred J . Sellers major . Recruitment started in early September 1861 and by December 900 men were raised . It was first sent to Baltimore and then to Washington , D . C . . Once there , it became part of the I Corps , Army of the Potomac , assigned to the 2nd Brigade , Second Division . After several months of garrison duty and railroad repair , the 90th was sent along with the rest of its division to the Shenandoah Valley to stop Major General T . J . Jackson ' s force , but did not get into any battles . In June , it was assigned to Major General John Pope ' s Army of Virginia . The regiment relieved part of the Union force after the Battle of Cedar Mountain . It lost 200 men during the Second Battle of Bull Run . At the Battle of Antietam , the 90th fought in the Cornfield in support of the Pennsylvania Reserves . Total losses during this battle were ninety - eight , including several officers . Lyle was promoted to command of the brigade , with Leech taking command of the regiment . Missing the Battle of Fredericksburg in December , it did fight on the Union left during the Battle of Chancellorsville . On July 1 , 1863 , at the Battle of Gettysburg , it was placed in support of the Union line on McPherson ' s Ridge . Forced to retreat with the rest of the I Corps , it was assigned with the rest of the division to the southern end of Cemetery Ridge . The chaplain of the regiment , Horatio Stockton Howell , was cruelly murdered on the steps of the Lutheran Church during the retreat . Lyle was temporarily appointed to command of the 1st Brigade , with Sellers taking over the regiment . It did not fight during the rest of the battle , suffering only some shelling . In early 1864 , the I Corps was consolidated into the V Corps , with the 90th forming part of the 1st Brigade , Second Division . The regiment lost heavily during the Overland Campaign , losing 124 out of 251 men at the Battle of the Wilderness and another hundred at Spotsylvania Court House . On May 6 , Lyle was placed in command of the 1st Brigade , Second Division . Since both Leech and Major Jacob M . Davis were on detached duty , Captain William P . Davis took command of the regiment . The 90th fought in the Siege of Petersburg . On June 24 , both Leech and Jacob Davis returned to the regiment , with Leech assuming command . At the Battle of Globe Tavern , Leech , Jacob Davis , and about 90 men were captured when the Confederates overran its position . Another twenty men were killed or wounded . William Davis took command of the regiment again . The original term of service for the 90th ran out on November 26 . Those eligible for discharge were sent to Philadelphia , Pennsylvania and the regiment was disbanded . The veterans and recruits whose enlistments had not expired yet were assigned to the 11th Pennsylvania Infantry .