The One Hundred and Thirty-eighth Infantry was enrolled for serviceduring the month of May.  This Regiment rendezvoused at Camp Wood, Quincy, Ill., and was mustered into the United States service June 21, 1864, with Colonel J. W. Goodwin as Colonel commanding.

On the 26th  day of June the Regiment was directed by the Secretary of War to proceed to Fort Leavenworth, Kansas, and there to report to Major General Samuel R. Curtis, commanding the Department of Kansas.  The Regiment was assigned to garrison duty at Fort Leavenworth, with Colonel as Post Commander.

This Regiment contained many veterans, whose discipline did not fail to give it the character of experience, and whose previous honorable service infused into its ranks a spirit of praiseworthy and patriotic emmulation.

At this time the counties of Jackson, Clay, Platt, Ray and Lafayette, and other counties along the western border of Missouri was over-run and in possession of bands of guerrillas and bushwhackers under the command of the noted Bill Anderson, Cy Gordon and Coon Thornton.  Early in July Major Tunnison with companies C and F, was ordered to occupy the post of Weston, Missouri, and operate from this point in driving the guerrillas from this territory.  During the months of July, August and a portion of Septmeber these companies were in active service, scarcely a day passing without a conflict with some of the horde of desperadoes infesting that community.  Early in the month of September, having cleared the counties spoken of, of guerrillas and bushwhackers, companies C and F returned to Fort Leavenworth to countinue their services in garrison duty. At the expiration of the term of service the regiment returned to Camp Butler, near Springfield, for muster out.

At this time General Price, commanding the Trans-Mississippi Army, invaded the State of Missouri from the southeast, driving General Ewing, who occupied Pilot Knob from the entrenchments and taking possession of that part of the State, thus cutting off communication between St. Louis and the southeast.  The safety of St. Louis and the entire State of Missouri was threatened by this invasion.  General Rosencrans was in command of the Department of Missouri, and was at the head of an inadequate and poorly appointed army contending against fearful odds for the preservation of the city and entire State.  This regiment voluntarily extended its term of service, and, by direction of the Secretary of War, proceeded to St. Louis and there reported to General Rosencrans for duty.

The duty of opening up the communication between the South and East part of the State was assigned to this Regiment.  They proceeded along the Iron Mountain Railroad as far as Ironton, Comapny C occupying the advance in guarding railway bridges from destruction by the rear of Price's Army. After General Price and his army was driven from the State this Regiment again returned to Camp Butler and was mustered out of the United States service on the 14th day of October.