99th Pennsylvania Infantry Regiment

99th Pennsylvania Infantry Regiment
Unit name	99th Pennsylvania Infantry Regiment
Caption	Regiment flag
Dates	1861–1865
Country	United States
Allegiance	Union
Branch	Infantry
Size	Regiment
Garrison	Philadelphia, Pennsylvania
Notable commanders	Alexander Hays, Thomas A. Smyth

99th Pennsylvania Infantry Regiment was an infantry regiment raised in Pennsylvania that served in the Union Army during the American Civil War. Organized in Philadelphia in 1861, the regiment served in multiple campaigns of the Eastern Theater, including operations under the Army of the Potomac and actions against forces of the Confederacy. The unit fought at major engagements such as Antietam, Fredericksburg, Chancellorsville, and Gettysburg, and its veterans later participated in occupation duties during the Appomattox Campaign.

Formation and Organization

The regiment was mustered in during 1861 at Philadelphia and drew recruits from counties including Lancaster, Bucks, and Chester. Initial officers included men with prior militia experience from organizations such as the 16th Regiment, Pennsylvania Volunteers and members of civic institutions like the Union League of Philadelphia. The 99th was assigned to brigades within divisions commanded by leaders from the Army of the Potomac, and it operated alongside regiments from New Jersey, New York, and Massachusetts.

Service History

After mustering, the regiment joined the Peninsula Campaign forces and participated in the Seven Days Battles under corps commanders in the Army of the Potomac structure. During the Maryland Campaign it engaged at South Mountain and Antietam as part of divisions moving along the Potomac River. In 1863 the 99th took part in the Chancellorsville Campaign and marched to defend Gettysburg during the Gettysburg Campaign. Later service included steady campaigning during the Overland Campaign, actions near Cold Harbor, and operations in the Siege of Petersburg before moving toward the Appomattox Campaign and the final surrender at Appomattox Court House.

Major Engagements and Battles

The regiment saw combat at several major battles of the Eastern Theater: - Seven Days Battles: skirmishing during the withdrawal from the Peninsula Campaign. - South Mountain and Antietam: engaged in the Maryland maneuver against forces of Robert E. Lee and the Army of Northern Virginia. - Fredericksburg: part of assaults against entrenched positions near the Rappahannock River. - Chancellorsville: actions amid maneuvers near Rappahannock and Spotsylvania. - Gettysburg: held positions on the Union lines against attacks associated with commanders like James Longstreet and Richard S. Ewell. - Overland Campaign and Siege of Petersburg: heavy fighting during operations led by Ulysses S. Grant and George G. Meade culminating in the Appomattox Campaign.

Commanders and Notable Personnel

Regimental leaders included field officers who later held division or corps posts in the Army of the Potomac; among them were colonels and lieutenant colonels who served with distinction alongside generals such as George B. McClellan, Ambrose Burnside, Joseph Hooker, and George G. Meade. Notable figures associated with the regiment included officers promoted for gallantry in actions connected to Antietam and Gettysburg, and enlisted men who received recognition from state authorities in Pennsylvania and civic institutions like the Soldiers' Monument committees.

Casualties and Strength

At muster the regiment's authorized strength approximated standard Union regiment complements and fluctuated with recruitment, disease, and battlefield losses common in units of the Army of the Potomac. The 99th sustained casualties at major engagements including Antietam, Fredericksburg, Chancellorsville, and Gettysburg, and later losses during the Overland Campaign and the Siege of Petersburg. Surviving veterans participated in Grand Army of the Republic posts and state veteran organizations in Pennsylvania after the war.

Equipment and Uniforms

Soldiers of the regiment were issued arms and accoutrements standard to the Union Army infantry, including Springfield Model 1861 rifled muskets and bayonets, cartridge boxes, and standard issue belts. Uniforms followed regulations promulgated by the United States Army with variations introduced by private purchase and wartime shortages; many troopers wore regulation frock coats or sack coats and kepis typical of Union infantry regiments. Camp equipment and tents mirrored those used across the Army of the Potomac during major campaigns.

Legacy and Commemoration

Veterans of the regiment were active in commemorations such as Memorial Day observances and reunions of the Grand Army of the Republic, and they contributed to monuments and markers on battlefields including Antietam National Battlefield and Gettysburg National Military Park. Regimental histories and rosters were compiled by Pennsylvania historical societies and featured in archival collections at institutions like the Historical Society of Pennsylvania and state archives, ensuring the 99th's service is represented in studies of the Civil War and preserved in military history scholarship.

Category:Units and formations of the Union Army from Pennsylvania Category:Pennsylvania Civil War regiments