7th Cavalry Regiment
While neither ride horses into battle today, the U.S. 7th Cavalry Regiment, existing as two battalions (called squadrons) assigned to the 1st Cavalry Division and three battalions in other divisions, has one of the more colorful histories among United States Army units. Although only part was wiped out at the Battle of the Little Big Horn under the command of George Armstrong Custer, it will always be known as the "Custer Regiment". That history was very much in the minds of helicopter-riding 7th Cavalry troopers at the Battle of the Ia Drang, in the intense fighting at LZ X-Ray and the even more desperate combat at LZ Albany.
It is no longer actually organized as a regiment, but battalions that trace their lineage to it still use the traditional song and greeting "Garryowen" after an Irish ballad.