The idea of breaking this line by an expedition up the Tennessee and Cumberland Rivers seems to have presented itself to many. Colonel Charles Whittlesy, of the Twentieth Ohio, a graduate of West Point and formerly in the army, while acting as Chief Engineer on the staff of General O.M. Mitchell in Cincinnati, wrote to General Halleck, November 20, 1861, suggesting a great movement by land and water up the Cumberland and Tennessee Rivers, on the ground that this was the most feasible route into Tennessee, and would necessitate the evacuation of Columbus and the retreat of Buckner from Bowling Green. In December, 1861, General Sherman, conversing with General Halleck, in St. Louis, suggested that the proper place to break the line was the centre, to which Halleck assented, pointing on the map to the Tennessee River, and saying that is the true line of operations. On January 3, 1862, General D.C. Buell, in a letter to General Halleck, proposed a combined attack on the centre and flanks of General Johnston's line, and added: "The attack on the centre should be made by two gunboat expeditions, with, I should say, 20,000 men on the two rivers." General Halleck, writing to General McClellan, January 20, 1862, said a movement down the Mississippi was premature; that a more feasible plan was to move up the Cumberland and Tennessee, making Nashville the objective point, which movement would threaten Columbus and force the abandonment of Bowling Green, adding "but the plan should not be attempted without a large force--not less than 60,000 men." General McClellan, however, thought such a movement should be postponed for the present. He wrote on January 6th, to General Buell, Commander of the Department of the Ohio, which department included all of Kentucky east of the Cumberland River: "My own general plans for the prosecution of the war make the speedy occupation of East Tennessee and its lines of railway matters of absolute necessity. Bowling Green and Nashville are in that connection of very secondary importance at the present moment." General Grant wrote no reasoned speculations about it, but throughout January pressed Halleck for permission to make the attempt. [Illustration: The Line from Columbus to Bowling Green.]