Learning that a hospital-boat under charge of Dr.Hough was preparing to start for Pittsburg Landing, I obtained the Doctor's consent to take passage on it, and on the evening of April 15, I left St.Louis for the scene of military operations in northeastern Mississippi.
At Pittsburg Landing I reported to General Halleck, who, after some slight delay, assigned me to duty as an assistant to Colonel George Thom, of the topographical engineers.

Colonel Thom put me at the work of getting the trains up from the landing, which involved the repair of roads for that purpose by corduroying the marshy places.
This was rough, hard work, without much chance of reward, but it, was near the field of active operations, and I determined to do the best I could at it till opportunity for something better might arise.
General Halleck did not know much about taking care of himself in the field.

His camp arrangements were wholly inadequate, and in consequence he and all the officers about him were subjected to much unnecessary discomfort and annoyance.

Someone suggested to him to appoint me quartermaster for his headquarters, with a view to systematizing the establishment and remedying the defects complained of, and I was consequently assigned to this duty.

Shortly after this assignment I had the satisfaction of knowing that General Halleck was delighted with the improvements made at headquarters, both in camp outfit and transportation, and in administration generally.