Rousseau was much predisposed, by reason of his mental organization, to excitability under fire, but it did not detract from his administrative power. He was as clearly administrative in danger as the more phlegmatic Thomas or Grant, but in a different way. Rousseau made very little, if any, use of his aids. If he had an order to give, he galloped across the field and gave it himself. If he had an advance to order, it was done by leading the troops in person. During this battle of Perryville, General McCook sent me to inform Rousseau, who was on the extreme left of the line, that his right was being turned and was falling back. Rousseau galloped to the endangered part of the line and rallied the troops in retreat, beating and cursing them into line, and actually breaking his sword over the head of one demoralized individual, who was thus brought to a stand. The enemy, however, continued to advance, and Rousseau was compelled to look around for farther assistance. Seeing Captain Charles O. Loomis's battery in position, in reserve, commanding a little valley into which the enemy had deployed, and through which they were rapidly advancing, he rode up to Captain Loomis and ordered him to open with canister. Loomis had not perceived the advancing enemy, and explained to Rousseau that he had been ordered into reserve by General McCook, and told to reserve his fire for close work. "Close work!" exclaimed Rousseau; "what the devil do you call that, Captain Loomis?" He pointed down the valley, and Loomis saw in an instant the advancing foe and his own danger. Loomis was a minute-man--one of the quickest-witted and brightest-eyed men I ever met--and in a second his six guns were pouring a destructive cross-fire into the rebel ranks that at once played havoc with the enemy and encouraged our own forces. The enemy thus advancing had flanked Lytle's brigade, and it was now falling back toward Loomis's position, but Rousseau's personal direction and appearance (Lytle had been left for dead on the field), and the opening guns of Loomis, soon reassured the men in retreat, and the line re-formed. About the same time Sheridan's brigade was ordered in on the left by General Buell, and the enemy were speedily and bloodily repulsed.