Halleck assumes command in the field—the advance upon Corinth —occupation of Corinth—the army separated.
General Halleck arrived at Pittsburg landing on the 11th of April and immediately assumed command in the field. On the 21st General Pope arrived with an army 30,000 strong, fresh from the capture of Island Number Ten in the Mississippi River. He went into camp at Hamburg landing five miles above Pittsburg. Halleck had now three armies: the Army of the Ohio, Buell commanding; the Army of the Mississippi, Pope commanding; and the Army of the Tennessee. His orders divided the combined force into the right wing, reserve, centre and left wing. Major-General George H. Thomas, who had been in Buell’s army, was transferred with his division to the Army of the Tennessee and given command of the right wing, composed of all of that army except McClernand’s and Lew. Wallace’s divisions. McClernand was assigned to the command of the reserve, composed of his own and Lew. Wallace’s divisions. Buell commanded the centre, the Army of the Ohio; and Pope the left wing, the Army of the Mississippi. I was named second in command of the whole, and was also supposed to be in command of the right wing and reserve.
Orders were given to all the commanders engaged at Shiloh to send in their reports without delay to department headquarters. Those from officers of the Army of the Tennessee were sent through me; but from the Army of the Ohio they were sent by General Buell without passing through my hands. General Halleck ordered me, verbally, to send in my report, but I positively declined on the ground that he had received the reports of a part of the army engaged at Shiloh without their coming through me. He admitted that my refusal was justifiable under the circumstances, but explained that he had wanted to get the reports off before moving the command, and as fast as a report had come to him he had forwarded it to Washington.
Preparations were at once made upon the arrival of the new commander for an advance on Corinth. Owl Creek, on our right, was bridged, and expeditions were sent to the north-west and west to ascertain if our position was being threatened from those quarters; the roads towards Corinth were corduroyed and new ones made; lateral roads were also constructed, so that in case of necessity troops marching by different routes could reinforce each other. All commanders were cautioned against bringing on an engagement and informed in so many words that it would be better to retreat than to fight. By the 30th of April all preparations were complete; the country west to the Mobile and Ohio railroad had been reconnoitred, as well as the road to Corinth as far as Monterey twelve miles from Pittsburg. Everywhere small bodies of the enemy had been encountered, but they were observers and not in force to fight battles.