Army - 1st Battalion 155th Infantry - Operation Iraqi Freedom wtih Map - MugThe "Mississippi Rifles" or the 155th Infantry Regiment, is Mississippi's oldest National Guard unit. Its history predates statehood, back to June 1799, and it is the seventh oldest infantry regiment in the United States Army. They patrolled the frontiers of the Mississippi Territory, captured Aaron Burr, defended Fort Mims during the Indian Wars, and served under General Andrew Jackson in the Battle of New Orleans in the War of 1812.