Established 20 December 1860 as the Independent Volunteer Battalion of Macon to contain all-volunteer militia companies in that city, including the Macon Volunteers (organized in 1825) and the Floyd Rifles (organized in 1841). Entered Confederate States service 20 April 1861; reorganized 22 April 1861 as the 2d Battalion, Georgia Infantry, to consist of the following companies: City Light Guards (Columbus), Floyd Rifles (Macon), Spalding Grays (Griffin), and Macon Volunteers (Macon). Surrendered 9 April 1865 at Appomattox Court House, Virginia, and paroled.

Reorganized 15 June 1874 as the 2d Battalion, Georgia Volunteers, to include following volunteer militia companies; Baldwin Blues (organized 11 May 1810 at Milledgeville), Floyd Rifles (Macon), Macon Volunteers (Macon), and Putnam Rifles (organized in 1856 at Eatonton). (Southern Cadets [Macon] assigned to the battalion in 1883.) Expanded and re-designated as the 2d Infantry, Georgia Volunteers, 23 January 1891.

Elements consolidated with elements of the 1st and 4th Regiments, Georgia Volunteers, and mustered into Federal service 11-14 May 1898 at Griffin as the 1st Georgia Volunteer Infantry; did not serve outside continental United States. Mustered out 18 November 1898 at Macon and resumed State status as 2d Infantry, Georgia Volunteers. (Georgia Volunteers re-designated Georgia State Troops 21 December 1899; re-designated Georgia National Guard 1 October 1905.) (4th Separate Battalion of Infantry, Georgia National Guard [organized 16 July 1884 as 7th Battalion, Georgia Volunteers] consolidated with the 2d Infantry 1 August 1912.)

Mustered into Federal service 2 July 1916 at Macon for Mexican Border and stationed at El Paso, Texas; returned to Macon 27 March 1917 but not mustered out; drafted into Federal service 5 August 1917. (Companies B [Macon Volunteers], C [Floyd Rifles], and F [Macon Hussars], reorganized to form the 151st Machine Gun Battalion and assigned to the 42d Division 20 August 1917.)

Consolidated with separate Companies F, H, and I, Georgia Infantry (formerly 3d Separate Battalion of Infantry), re-designated (less Companies B, C, and F) as the 121st Infantry and assigned to the 31st Division 1 October 1917. Skeletonized in France in November 1918 and demobilized 14

January 1919 at Camp Gordon, Georgia. (151st Machine Gun Battalion demobilized in May 1919 at Camp Gordon.)

Former 2d Infantry, Georgia National Guard, reorganized (less former 3d Separate Battalion of Infantry) 2 August,29 November 1920 as the 2d Battalion, 1st Infantry, Georgia National Guard. Expanded as the 1st Infantry, Georgia National Guard and Federally recognized 31 May 1921 with Headquarters at Macon. Re-designated 27 April 1922 as the 122d Infantry. Re-designated 9 June 1924 as the 121st Infantry.

Campaigns

Civil War (Confederate service) 

Peninsula 

Fredericksburg 

Chancellorsville 

Gettysburg 

Appomattox

World War I