The Distinctive Unit Insignia (AKA “unit crest” or DUI) of the 155th Infantry Regiment was approved 4 June 1931. Its shield contains both blue and white backgrounds to reflect current (blue) and old (white) Infantry colors and the organization’s longtime status in that branch. On the lower left of the shield portion of the insignia, a cactus denotes combat service during the Mexican War; the fleur-de-lis beside it is for World War I service. In the chief (top third of shield), an arrow and a cross represent service in the Indian Wars and the War of 1812. “Stand Fast,” the unit motto on a scroll at the bottom, is a truncated version of the command (“Stand Fast, Mississippians!”) that then-Colonel Jefferson Davis gave the Regiment during the Battle of Buena Vista in the Mexican War.
Distinctive Unit Insignias are worn by all Soldiers (except General Officers) in units that have been authorized to be issued the device. It is worn centered on the shoulder loops of the Army Green Service Uniform (AGSU) and the blue Army Service Uniform (ASU, Enlisted only) with the base of the insignia toward the outside shoulder seam. DUIs are not worn on the Dress variations of either uniform, however.More guidance on wear of the DUI is found in DA Pamphlet 670-1, Section 21-22, "Distinctive unit insignia" and 21–3(d) and (e), "Beret" and "Garrison Cap," respectively.
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With a lineage that goes back to October 1798 and the organization of the Legion of Militia of the Lower or Southern District, Mississippi Territory as the Militia of Adams County, the 155th Infantry Regiment is one of just two dozen current active National Guard units whose lineage includes credits for campaign participation in the War of 1812. Ordered into Federal service twice during the war, the Regiments’ forebears fought in the War’s most famous tilt, the Battle of New Orleans, while designated as the Mississippi Territorial Militia. But it wasn’t the organization’s first time in combat: It had fought in the campaign against the Creek Indians in 1813 and 1814.
The Mississippi Territorial Militia would be organized in early 1846 as the 1st Mississippi Infantry Regiment, or “Mississippi Rifles”—later selected as the unit’s official special designation or nickname—to serve in two campaigns in the Mexican War. The Regiment was led by none other than Colonel Jefferson Davis, who would of course go on to be the Regiment’s most superior commander as the President of the Confederate States of America. During the Civil War, the Regiment would fight in ten campaigns, with nine taking place after the unit’s surrender at Fort Donelson in 1862 and its subsequent reorganization using captured Soldiers who were recovered during a prisoner exchange.
It wasn’t until 1917 that the organization received its current designation with the drafting of the 1st Infantry, Mississippi National Guard into Federal service and its reorganization into the 155th Infantry. It was assigned to the 39th Division, which became a replacement division (the 5th Depot) after arriving in France; the Regiment earned an uninscribed World War I campaign streamer for providing trained replacement troops for the front-line combat divisions. During World War II, the 155th would serve with the 31st Infantry Division and take part in two World War II campaigns in the Asiatic-Pacific, with an Arrowhead device for the New Guinea campaign streamer denoting the Regiment’s participation in an assault landing. It was also awarded a Philippine Presidential Unit Citation.
The 155th would not see combat again until the launch of the War on Terrorism. Ordered into Federal service in 2004 and 2009, the Regiment—organized to consist of a single battalion since 1968—would be tapped for a Navy Unit Commendation while earning credit for Iraqi Sovereignty campaign. Today, the 1st Battalion, 155th Infantry Regiment is a component of the 155th Armored Brigade Combat Team and is headquartered in Tupelo, Mississippi.