Recognizing its tenacity in combat at the Battle of Antietam, Brigadier General William French assigned the nickname as a comparison to the steadfastness of the Rock of Gibraltar.
The 4th Ohio Infantry Regiment was forced to miss the Maryland Campaign due to regiment-wide sickness but was otherwise a consistent member of the Brigade.
During the Battle of East Cemetery Hill at Gettysburg on July 2, 1863, nine cannons from Wiedrich's and Ricketts' Batteries had been silenced and remained in violently disputed possession.
Three regiments from the Gibraltar Brigade marched in column at double-quick time from Zeigler's Grove across the length (west to east) of Evergreen Cemetery.
The column split into two at the Gatehouse (with the 7th West Virginia on its left side and the 8th Ohio and the 14th Indiana on its right), crossed the Baltimore Pike, left-faced into line of battle, and attacked with bayonets.