WASHINGTON, February 15, 1862-8 p.m.

Major-General HALLECK, Saint Louis:

Have telegraphed to Buell to help you by advancing beyond Bowling Green on Nashville; or, if that be be too slow, via Cumberland.

GEO. B. McCLELLAN,

Major-General.

SAINT LOUIS, February 15, 1862-8 p.m.

Major General GEORGE B. McCLELLAN:

General Buell telegraphs that he purposes to move from Bowling Green on Nashville. This is bad strategy. Moreover, the roads are very muddy and all the bridges destroyed. His forces should come and help me to take Fort Donelson and Clarksville and move on Florence, Ala., cutting the railroad at Decatur. Nashville would then be abandoned, precisely as Bowling Green has been, without a blow. With troops in mass on the right points the enemy must retire, and Tennessee will be freed, as Kentucky has been; but I have not forces enough to make this new strategic move and at the same time observe Columbus. Give me the forces required and I will insure complete success. Price is still in retreat, with General Curtis in pursuit.

H. W. HALLECK,

Major-General.

FEBRUARY 15-10 p.m.

Major-General HALLECK, Saint Louis:

Buell will move in force on Nashville as rapidly as circumstances will permit. If Grant's position renders it absolutely necessary Buell will re-enforce him with three brigades and three batteries to-morrow, but I think them better employed in the direct advance upon Nashville.

GEO. B. McCLELLAN,

Major-General, Commanding.

WASHINGTON, February 15-11 p.m.

Major-General HALLECK, Saint Louis:

Yours of 8 p.m. received. Your idea is in some respects good. But if Buell can rapidly advance on Nashville he will take it and cut off the enemy who are near Fort Donelson, if they do not retreat immediately. His advance in force beyond Bowling Green will at once relieve Grant. His orders are to re-enforce Grant if he cannot reach Nashville in time. The immediate possession of Nashville is very important. It can best be gained by the movement I have directed. The possession of Decatur will not necessarily cause the rebels to evacuate Nashville, you must also threaten to occupy Stevenson to accomplish that. I do not see that Buell's movement is bad strategy, for it will relieve the pressure upon Grant and lead to results of the first importance. If the destruction of the railroad is so extensive as to make the operation impracticable or very difficult and slow, I have provided for the alternative in my instructions to Buell. Enable Grant to hold his own, and I will see that Buell relieves him. The Decatur movement and one on Memphis are the next steps in my programme.