June 19, 1916, President Woodrow Wilson calls into service 135,000 National Guardsmen. War with Mexico seemed imminent, and there weren't enough federal troops available to meet demands.

A report submitted by Brigadier General William A. Mann, Chief of the Militia Bureau (now the National Guard Bureau), stated that "the mobilization was the outcome of a national emergency demanding extra military service beyond that which could be furnished by the Regular Army....The Regular Army on the Mexican border could be [reinforced] no other way".

As a result, Mississippi assembled one war strength regiment under the colors of the 1st Mississippi Infantry in Jackson. Colonel George C. Hoskins served as the regimental commander, and the following as the 1st, 2nd, and 3rd Battalion commanders: Major George E. Hogaboom, Major C.R. Dalby, and Major A.H. Patterson.

To honor and remember this period of service, the Regiment produced the "Invasion of Texas, First Mississippi Infantry". This book was edited by T. Mitchell Robinson and Harold E. Gardinier, both members of the Regiment.

The regimental units include:

Headquarters Company & Regimental Band, Macon

• Sanitary Detachment, Biloxi
• Company A, Vicksburg
• Company B, Natchez
• Company C, Greenville
• Company D, Vicksburg
• Company E, Yazoo City
• Company F, Jackson
• Company G, Hattiesburg
• Company H, Brookhaven
• Company I, Columbus
• Company K, Kosciusko
• Company L, West Point
• Company M, Laurel

The following companies were formed following muster, and are not associated with a hometown:

• Supply Company
• Machine Gun Company

Download the book as an Adobe Acrobat file here: "Invasion of Texas, First Mississippi Infantry".
^{This book that belonged to Harry S. Mimmick, from Collins, who enlisted on July 3, 1916, and was a member of the regimental band.}