30th Missouri Volunteer Infantry The 30th Missouri Volunteer Infantry , also known as the " Shamrock Regiment " was an infantry regiment that served in the Union Army during the American Civil War . It was a sister unit to the 7th Missouri Volunteer Infantry ( the " Irish Seventh " ) and in 1864 was consolidated with a battalion of veteran volunteers of that regiment and operated as a " demi - brigade " known popularly as the " Missouri Irish Brigade " . Service . The 30th Missouri Volunteer Infantry , was organized at St . Louis Missouri in the autumn of 1862 and mustered in for three years service . It was often referred to as the " Shamrock Regiment " due to the large number of Irish immigrants who were enlisted in its ranks . Organized at St . Louis , Mo . , September and October , 1862 . Attached to Cape Girardeau , Mo . , Dept . of Missouri , to December 1862 . 1st Brigade , 11th Division , Right Wing 13th Army Corps ( Old ) , Department of the Tennessee , December 1862 . 1st Brigade , 4th Division , Sherman ' s Yazoo Expedition , to January 1863 . 1st Brigade , 1st Division , 15th Army Corps , Army of the Tennessee , to August 1863 . Post of Vidalia , District of Natchez , Miss . , Dept . of Tennessee , to April 1864 . 1st Brigade , 1st Division , 17th Army Corps , Dept . of Tennessee , to August 1864 . 1st Brigade , 2nd Division , 19th Army Corps , Dept . of the Gulf , to December 1864 . 2nd Brigade , Reserve Division , Military Division West Mississippi , to February 1865 . 3rd Brigade , 1st Division , Reserve Corps , Military Division West Mississippi , to February 1865 . 3rd Brigade , 1st Division . 13th Army Corps ( New ) , Military Division West Mississippi , to July 1865 . Dept . of Texas to August 1865 . Detailed service . Duty at Cape Girardeau , Mo . , till November 10 , 1862 . Moved to Patterson , Missouri , November 10 – 17 , and return to Cape Girardeau November 25 – 29 . Moved to Helena , Ark . , December 8 – 16 . Sherman ' s Yazoo Expedition December 22 , 1862 , to January 3 , 1863 . Chickasaw Bayou December 26 – 28 . Chickasaw Bluff December 29 . Expedition to Arkansas Post , Ark . , January 3 – 10 , 1863 . Assault and capture of Fort Hindman , Arkansas Post , January 10 – 11 . Moved to Young ' s Point , La . , January 17 – 23 , and duty there till March . At Milliken ' s Bend , La . , till April . Expedition to Greenville , Black Bayou and Deer Creek April 2 – 14 . Demonstration on Haines ' and Drumgould ' s Bluffs April 29 - May 2 . Moved to Join army in rear of Vicksburg , Mississippi , via Richmond and Grand Gulf , May 2 – 14 . Jackson , Miss . , May 14 . Siege of Vicksburg , Miss . , May 18 - July 4 . Assaults on Vicksburg May 19 and 22 . Advance on Jackson , Miss . , July 4 – 10 . Siege of Jackson July 10 – 17 . Ordered to District of Natchez , Miss . , August 15 . Assigned to garrison duty at post of Vidalia till April 1864 . Action at Vidalia September 14 , 1863 . Expedition to Trinity November 15 – 16 . Expedition to Tensas River February 2 – 3 , 1864 . Repulse of Gen . Polignac ' s threatened attack on Vidalia February 17 , 1864 . Expedition to Tensas River March 10 – 11 . Moved to Vicksburg , Miss . , April 3 – 5 , and duty there till May 9 . Expedition to Big Black River Bridge May 9 – 16 . Camp at Vicksburg till July 1 . Pearl River Expedition July 1 – 10 . Guard pontoon train at Big Black River July 3 – 9 . Moved to Morganza July 28 – 30 , thence to Port Hudson , Louisiana , August 23 – 24 . Expedition to Clinton August 24 – 27 . Moved to Morganza August 28 , and to mouth of White River , Ark . , September 3 – 8 . Duty there till October 18 . Moved to Memphis , Tenn . , October 18 – 19 . At Fort Pickering , Memphis , till October 28 . Moved to mouth of White River , Ark . , October 28 – 29 , thence to Duvall ' s Bluff , Ark . , November 7 – 10 , and to Memphis , Tenn . , November 27 - December 1 . Consolidated to a Battalion of 4 Companies November 30 . Moved to Kenner , La . , January 2 – 8 , 1865 ; thence to Dauphin Island February 11 – 18 . Campaign against Mobile , Ala . , and its Defences March 17 - April 12 . Siege of Spanish Fort and Fort Blakely March 26 - April 8 . Assault and capture of Fort Blakely April 9 . Occupation of Mobile April 12 , and camp there till May 10 , and at Fort Blakely and Fort Tracy till June 8 . At Mobile till June 28 . Moved to Galveston , Texas , June 28 - July 1 , thence to Columbus July 9 – 11 . Post duty at Allayton till August 21 . Mustered out at Columbus , Texas , August 31 , and discharged at St . Louis , Mo . , September 11 , 1865 . Casualties . Regiment lost during service 2 Officers and 10 Enlisted men killed and mortally wounded and 1 Officer and 280 Enlisted men by disease . Total 293 .