Many subjects presented themselves for investigation, any one of which would, in ordinary times, have required the exclusive attention of a separate committee, and to follow out every line of inquiry suggested was manifestly a practical impossibility. Therefore the committee decided not to undertake any investigations into what might be considered side issues, but to keep their attention directed entirely to the essential features of the war, so that they could ascertain and comprehend the necessities of the armies and the causes of disaster or complaint, and the methods of supplying the one and remedying the other. Attempts were made repeatedly to use its power to punish enemies or to avenge private grievances, but its members adhered resolutely to the straightforward course originally marked out as the path of its duty. The first subject which the committee carefully inquired into was the defeat at Bull Run. Many witnesses were examined, chiefly officers who were engaged in the battle--Generals Scott, McDowell, Meigs, Heintzelman, Butterfield, Fitz-John Porter, and others. The testimony was very voluminous, but the committee reached an early and unanimous opinion as to the causes of the disaster. Their report, written by Mr. Wade, said: "That which now appears to have been the great error was the failure to occupy Centreville and Manassas at the time Alexandria was occupied, in May. The position at Manassas controlled the railroad connections in all that section of the country.... The next cause of disaster was the delay in proceeding against the enemy until the time of the three months' men was nearly expired. The enemy were allowed time to collect their forces and strengthen their position by defensive works.... There had been but little time devoted to disciplining the troops and instructing them, even in regiments; hardly any instruction had been given them in brigade movements, and none at all as divisions." General McDowell prepared a plan of campaign, which was approved by the Cabinet, and the 9th of July was fixed upon as the day for the advance; but the movement did not commence until a week later than the appointed time. Transportation was deficient, and there was much delay resulting from lack of discipline among the troops, and when the battle came the Union forces were fatigued and not in good fighting condition. "But," said the report, "the principal cause of the defeat was the failure of General Patterson to hold the troops of General Johnston in the valley of the Shenandoah." Patterson had 23,000 men, while Johnston had but 12,000. Still, Patterson disobeyed the orders of General Scott, which were to make offensive demonstrations against General Johnston so as to detain his army at Winchester, and if he retreated to follow him and keep up the fight. Those orders were repeated every day for more than a week in the telegraphic correspondence between Scott and Patterson. Finally, General Scott