Although he complimented McClellan and expressed his "great confidence in your intelligence, zeal, science, and energy", he replied by letter that the 80,000 men would be better used on a river-based expedition to control the Mississippi River and split the Confederacy, accompanied by a strong Union blockade of Southern ports.
Selv om han roste McClellan og udtrykte sin "store tiltro til Deres intelligens, iver, kundskaber og energi", svarede han i et brev at 80.000 mand ville være bedre anvendt i en flodbaseret ekspedition der skulle sikre kontrollen over Mississippifloden og dele Konføderationen, ledsaget af en stærk blokade af Sydstaternes havne.