The Army of the Potomac was the primary field army of the Union army in the Eastern Theater of the American Civil War. It was created in July 1861 shortly after the First Battle of Bull Run and was disbanded in June 1865 following the surrender of the Confederate Army of Northern Virginia in April.
The Irish Brigade was an infantry brigade, consisting predominantly of Irish Americans, who served in the Union Army in the American Civil War. The designation of the first regiment in the brigade, the 69th New York Infantry, or the "Fighting 69th," continued in later wars. The Irish Brigade was known in part for its famous war cry, the "Faugh a Ballaugh" which is an anglicization of the Irish phrase, fág an bealach, meaning "clear the way" and used in various Irish-majority military units founded due to the Irish diaspora. According to Fox's Regimental Losses, of all Union army brigades, only the 1st Vermont Brigade and Iron Brigade suffered more combat dead than the Irish Brigade during America's Civil War.
The XII Corps was a corps of the Union Army during the American Civil War.
The VI Corps was a corps of the Union Army during the American Civil War.
The 14th Indiana Infantry Regiment, called "The Gallant Fourteenth," was an infantry regiment and part of the Union Army's celebrated "Gibraltar Brigade" during the American Civil War. Mustered on June 7, 1861, it was the state's first regiment organized for three years' service. The 14th Indiana served in many major campaigns and battles mostly in the Eastern Theater. During its three years of service, the regiment had a total of 222 casualties.
The Philadelphia Brigade was a Union Army brigade that served in the American Civil War. It was raised primarily in the city of Philadelphia, Pennsylvania, with the exception of the 106th regiment which contained men from Lycoming and Bradford counties.
George Pierce Doles was an American businessman and Confederate general during the American Civil War. His men played a key role on the first day of the Battle of Gettysburg in driving back the Union XI Corps.
The 7th Ohio Infantry Regiment was an infantry regiment formed in northeastern Ohio for service in the Union Army during the American Civil War. It served in the Eastern Theater in a number of campaigns and battles with the Army of Virginia and the Army of the Potomac, and was then transferred to the Western Theater, where it joined the Army of the Cumberland besieged at Chattanooga. It was noted for its holding the high ground at the center of the line at Antietam as part of Tyndale's 1st Brigade, Greene's 2nd Division of Mansfield's XII Corps. It is of the 7th regiment that a war historian wrote, "All in all, considering the number of its battles, its marches, its losses, its conduct in action, it may be safely said that not a single regiment in the United States gained more lasting honor or deserved better of its country than the Seventh Ohio Volunteer Infantry."
The 16th Maine Infantry Regiment was an infantry regiment that served in the Union Army during the American Civil War. The regiment was one of five raised in answer to the July 2, 1862, call by Lincoln for 300,000 volunteers for three years. The state of Maine's quota was 9,609. It was particularly noted for its service during the 1863 Battle of Gettysburg.
The Iron Brigade, also known as The Black Hats, Black Hat Brigade, Iron Brigade of the West, and originally King's Wisconsin Brigade was an infantry brigade in the Union Army of the Potomac during the American Civil War. Although it fought entirely in the Eastern Theater, it was composed of regiments from three Western states that are now within the region of the Midwest. Noted for its excellent discipline, ferocity in battle, and extraordinarily strong morale, the Iron Brigade suffered 1,131 men killed out of 7,257 total enlistments: the highest percentage of loss suffered by any brigade in the United States Army during the war.
Archibald Livingston McDougall was an officer in the Union Army during the American Civil War who commanded the 123rd New York Volunteer Infantry early in the war and subsequently led a brigade at the Battle of Gettysburg.
Ezra Ayers Carman was an officer in the Union Army during the American Civil War, commanding a New Jersey infantry regiment and (occasionally) a brigade.
Henry J. Stainrook, occasionally spelled Steinrock, led a regiment of the Army of Virginia and the Army of the Potomac in the American Civil War. He briefly led a brigade at the Battle of Antietam. Stainrook was killed in the Battle of Chancellorsville.
The 5th Ohio Infantry Regiment was an infantry regiment from southwestern Ohio that served in the Union Army during the American Civil War, serving in both the Eastern and Western Theaters in a series of campaigns and battles. It was noted for its holding the high ground at the center of the line at Antietam as part of Tyndale's 1st Brigade, Greene's 2nd Division of Mansfield's XII Corps.
The 2nd Regiment Massachusetts Volunteer Infantry was an infantry regiment in the Union Army during the American Civil War. Major George H. Gordon, a West Point graduate and veteran of the Mexican–American War, organized the unit's recruitment and formation. The 2nd Massachusetts was trained at Camp Andrew in West Roxbury, Massachusetts on the site of the former Transcendentalist utopian community, Brook Farm. Roughly half the regiment was mustered in on May 18, 1861 and the remainder on May 25, 1861 for a term of three years. The regiment saw extensive combat as part of the Army of the Potomac particularly during the Battle of Antietam and the Battle of Gettysburg.
Jacob C. Higgins (1826–1893) was a commander of Pennsylvania troops who participated in both major military conflicts of his time, the Mexican–American War and the American Civil War. Among his Civil War commands, he guided the 125th Pennsylvania Infantry regiment under heavy fire during the Battle of Antietam and likewise during the Battle of Chancellorsville. Following the muster out and return home of the 125th PA, the Gettysburg Campaign sent cavalry under Confederate General John D. Imboden to threaten vital railroad resources at Altoona and iron production facilities in the Juniata River watershed; in response, Emergency Militia was organized by Colonel Higgins and minimized this northwestern incursion.
The 27th New York Infantry Regiment was an infantry regiment formed in Elmira, New York, to fight and defend the United States during the American Civil War. The regiment was also known as the "Union Regiment".
The 111th Pennsylvania Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War. It was noted for its holding the high ground at the center of the line at Antietam as part of Stainrook's 2nd Brigade, Greene's 2nd Division of Mansfield's XII Corps.
The 154th New York Infantry Regiment was an infantry regiment in the U.S. Army during the American Civil War.
Independent Battery F, Pennsylvania Light Artillery, also known as the "Pittsburg Battery", was an artillery battery that served in the Union Army during the American Civil War. Organized in December 1861, the unit first served in the Shenandoah Valley. Battery F fought at Hancock, Winchester, Sulphur Springs, Second Bull Run, Chantilly, and Antietam in 1862. The following year the unit fought at Chancellorsville, Gettysburg, the Bristoe Campaign, and Mine Run. In 1864–1865, Battery F fought at Morton's Ford and served in the garrisons of Washington, D.C., and Harper's Ferry, West Virginia before being mustered out in June 1865. One enlisted man from the battery won the Medal of Honor for heroic action at Gettysburg.
United States 
