Before the advance upon Manassas, General McClellan changed his plans, and demanded to be permitted to leave the enemy intrenched at Centreville and Manassas; to leave the Potomac blockaded, and to take his army to Annapolis by land, and there embark them for the rear of the enemy to surprise him. In the council of war called upon this proposition, the commanding general and eight out of twelve of the commanders of divisions (and here permit me to say that I am informed that seven out of the eight generals were appointed upon the recommendation of General McClellan) voted that it was not safe to advance upon the wooden guns of Centreville, and to adopt the new plan of campaign. The President and the Secretary of War overruled this pusillanimous decision, and compelled McClellan to "move immediately upon the enemy's works." He marched, and the trophies of that memorable campaign are known to the Senate and the country. At Fairfax, General McClellan changed his plan and decided not to advance upon the rebels with his whole force, but to return to Alexandria, divide his army, and embark for Fortress Monroe and Yorktown. It was decided that 45,000 men should be left for the defense of the capital, and he was permitted to embark. After much delay (unavoidable in the movement of so vast a force, with its enormous material) the general-in-chief himself embarked. Soon after he sailed it came to the knowledge of the Committee on the Conduct of the War that the capital, with its vast accumulation of material of war, had been left by General McClellan virtually without defense, and the enemy's whole force, large or small, was untouched in front. [Mr. Chandler here introduced the official testimony to prove that General McClellan had so denuded Washington as to compel the President to interpose and detain General McDowell's corps for its adequate defense. He then said:] The country has been deceived. It has been led to believe that the Secretary of War or somebody else has interfered with General McClellan's plans, when he had an army that could have crushed any other army on the face of the earth. One hundred and fifty-eight thousand of the best troops that ever stood on God's footstool were sent down to the Peninsula and placed under command of General McClellan; and yet the whole treasonable press of the country has been howling after the Secretary of War because of his alleged refusal to send reinforcements to General McClellan. As I said the other day, he has sent every man, every sabre, every bayonet, every horse, that could be spared from any source whatever to increase that grand army under General McClellan in front of Richmond. Why did he not enter Richmond? We shall see.... It is not for me, sir, to state the strength of McClellan's army at this time; but I know it is 158,000 men, less the number lost by sickness and casualties.