Since the fall of Fort Henry on February 6, a lively correspondence had been going on, in which General Halleck besought Buell to come with his available forces, assist in capturing Donelson, and command the column up the Cumberland to cut off both Columbus and Nashville. President Lincoln, scanning the news with intense solicitude, and losing no opportunity to urge effective coöperation, telegraphed Halleck:
"You have Fort Donelson safe, unless Grant shall be overwhelmed from outside: to prevent which latter will, I think, require all the vigilance, energy, and skill of yourself and Buell, acting in full coöperation. Columbus will not get at Grant, but the force from Bowling Green will. They hold the railroad from Bowling Green to within a few miles of Fort Donelson, with the bridge at Clarksville undisturbed. It is unsafe to rely that they will not dare to expose Nashville to Buell. A small part of their force can retire slowly toward Nashville, breaking up the railroad as they go, and keep Buell out of that city twenty days. Meantime, Nashville will be abundantly defended by forces from all south and perhaps from here at Manassas. Could not a cavalry force from General Thomas on the upper Cumberland dash across, almost unresisted, and cut the railroad at or near Knoxville, Tennessee? In the midst of a bombardment at Fort Donelson, why could not a gunboat run up and destroy the bridge at Clarksville? Our success or failure at Fort Donelson is vastly important, and I beg you to put your soul in the effort. I send a copy of this to Buell."
This telegram abundantly shows with what minute understanding and accurate judgment the President comprehended military conditions and results in the West. Buell, however, was too intent upon his own separate movement to seize the brilliant opportunity offered him. As he only in a feeble advance followed up the retreating Confederate column from Bowling Green to Nashville, Halleck naturally appropriated to himself the merit of the campaign, and telegraphed to Washington on the day after the surrender:
"Make Buell, Grant, and Pope major-generals of volunteers, and give me command in the West. I ask this in return for Forts Henry and Donelson."
The eagerness of General Halleck for superior command in the West was, to say the least, very pardonable. A vast horizon of possibilities was opening up to his view. Two other campaigns under his direction were exciting his liveliest hopes. Late in December he had collected an army of ten thousand at the railroad terminus at Rolla, Missouri, under command of Brigadier-General Curtis, for the purpose of scattering the rebel forces under General Price at Springfield or driving them out of the State. Despite the hard winter weather, Halleck urged on the movement with almost peremptory orders, and Curtis executed the intentions of his chief with such alacrity that Price was forced into a rapid and damaging retreat from Springfield toward Arkansas. While forcing this enterprise in the southwest, Halleck had also determined on an important campaign in southeast Missouri.
Next to Columbus, which the enemy evacuated on March 2, the strongest Confederate fortifications on the Mississippi River were at Island No. 10, about forty miles farther to the south. To operate against these, he planned an expedition under Brigadier-General Pope to capture the town of New Madrid as a preliminary step. Columbus and Nashville were almost sure to fall as the result of Donelson. If now he could bring his two Missouri campaigns into a combination with two swift and strong Tennessee expeditions, while the enemy was in scattered retreat, he could look forward to the speedy capture of Memphis. But to the realization of such a project, the hesitation and slowness of Buell were a serious hindrance. That general had indeed started a division under Nelson to Grant's assistance, but it was not yet in the Cumberland when Donelson surrendered. Halleck's demand for enlarged power, therefore, became almost imperative. He pleaded earnestly with Buell:
"I have asked the President to make you a major-general. Come down to the Cumberland and take command. The battle of the West is to be fought in that vicinity.... There will be no battle at Nashville." His telegrams to McClellan were more urgent. "Give it [the Western Division] to me, and I will split secession in twain in one month." And again: "I must have command of the armies in the West. Hesitation and delay are losing us the golden opportunity. Lay this before the President and Secretary of War. May I assume the command? Answer quickly."
But McClellan was in no mood to sacrifice the ambition of his intimate friend and favorite, General Buell, and induced the President to withhold his consent; and while the generals were debating by telegraph, Nelson's division of the army of Buell moved up the Cumberland and occupied Nashville under the orders of Grant. Halleck, however, held tenaciously to his views and requests, explaining to McClellan that he himself proposed going to Tennessee:
"That is now the great strategic line of the western campaign, and I am surprised that General Buell should hesitate to reinforce me. He was too late at Fort Donelson.... Believe me, General, you make a serious mistake in having three independent commands in the West. There never will and never can be any coöperation at the critical moment; all military history proves it."
This insistence had greater point because of the news received that Curtis, energetically following Price into Arkansas, had won a great Union victory at Pea Ridge, between March 5 and 8, over the united forces of Price and McCulloch, commanded by Van Dorn. At this juncture, events at Washington, hereafter to be mentioned, caused a reorganization of military commands and President Lincoln's Special War Order No. 3 consolidated the western departments of Hunter, Halleck, and Buell, as far east as Knoxville, Tennessee, under the title of the Department of the Mississippi, and placed General Halleck in command of the whole. Meanwhile, Halleck had ordered the victorious Union army at Fort Donelson to move forward to Savannah on the Tennessee River under the command of Grant; and, now that he had superior command, directed Buell to march all of his forces not required to defend Nashville "as rapidly as possible" to the same point. Halleck was still at St. Louis; and through the indecision of his further orders, through the slowness of Buell's march, and through the unexplained inattention of Grant, the Union armies narrowly escaped a serious disaster, which, however, the determined courage of the troops and subordinate officers turned into a most important victory.