155th Pennsylvania Infantry

The 155th Pennsylvania Volunteer Infantry Regiment was a Federal infantry regiment that served in the American Civil War in the Army of the Potomac in the Eastern Theater.

Recruits from the Pittsburgh area organized at Camp Copeland from September 2–19, 1862, into the 155th Regiment, Pennsylvania Volunteer Infantry. Edward J. Allen served as the first colonel. After initial training and drilling, the regiment moved via train to Washington, D.C. where it joined the 2nd Brigade, 3rd Division of the Union Fifth Corps. It moved to Sharpsburg, Maryland, after the Battle of Antietam and then first saw combat in December 1862 at the Battle of Fredericksburg, where the color guard suffered very high casualties in an ill-fated assault.

During their first years the regiment wore the regulation uniform of the Union Army, but in 1863 they, along with the 140th New York and 146th New York received Zouave uniforms. The three regiments were each given a different style Zouave uniform that varied in color. The 140th New York received a predominately dark blue traditional style Zouave uniform with red trim while the 146th New York was given a light blue uniform with yellow trim that resembled that worn by the French Tirailleurs or "Turcos" of Crimean War fame. The 155th Pennsylvania however received a unique Zouave uniform in a style never before created. It consisted of a French blue (not dark blue) Zouave jacket with yellow trim featuring very large yellow "tombeaus" (a stylized false pocket on the front of the jacket). A departure from the usual styled jacket was an inside false vest. A red Zouave sash with yellow trim, French Blue Zouave pantaloons, a red Zouave fez with yellow trim and a dark blue tassle completed the uniform. Slight variations in jacket styles can be seen in the unit's regimental history entitled "Under the Maltese Cross" published in 1910.

The 155th Pennsylvania along with the 140th New York and the 146th New York became the "Zouave Brigade" in the Army of the Potomac's Fifth Corps. The a brigade would later grow with the addition of the 5th New York.