Ferris was an adjutant in the 30th Massachusetts Infantry. On April 1, 1865, at Berryville, Virginia, accompanied only by an orderly, he was riding outside the Union lines when he was attacked by five of Mosby's guerrillas. It was not the custom of Mosby's men either to ask or give quarter or to take prisoners. Ferris who was well mounted could probably have escaped, but would have had to leave his orderly behind, as the latter's horse was a slow one. Accordingly, although both the men were armed only with sabres, Ferris made up his mind to fight to the death. Without waiting to be attacked, he spurred his horse at the guerrilla-leader and suddenly executing a demi-volte which is only effective when performed by a good sabre and a trained horse, he whirled like lightning and caught his opponent such a tremendous back-handed slash that he cut him almost to the saddle. As the man toppled over, Ferris slipped one arm around his waist and managed to unbuckle his pistol-belt and seize both of his pistols. He then at once engaged with another one of the band and while parrying and thrusting, saw out of the tail of his eye a third man aiming a revolver at him only a few yards away. Parrying a thrust from his opponent in front, Ferris simultaneously fired with the other hand. Although Ferris was shooting with his left hand, his bullet killed his opponent while the Confederate's fire struck Ferris just above the left knee, inflicting a painful but not dangerous flesh-wound. Ferris pressed his opponent in front still more vigorously and finally succeeded in wounding him so severely that he turned and bolted, leaving Ferris free to go to the rescue of his orderly, who had been putting up a good fight against the other two of the band. Ferris reached him just in time. He had been wounded twice and though fighting bravely, one of his antagonists had managed to reach a position in his rear. There was not much time for Ferris to do anything with his sabre. Everything must depend upon a pistol shot. Stopping his horse, he drew his remaining pistol, took careful aim and shot the man behind his orderly through the body just as the latter had his sabre uplifted for a last blow at the hardly-pressed Union officer. The remaining guerrilla, who had already been slightly wounded by the orderly, wheeled his horse and rode off leaving the two Union men in possession of the field and the spoils of war, consisting of two capital pistols and a magnificent riderless horse which they brought back with them. One of the most devoted deeds of courage in the war is chronicled last. On July 21, 1861, the first great battle of the war was fought at Bull Run, Virginia, not far from the federal capital. It was a disastrous day. Unorganized, commanded by inexperienced officers, that battle soon became the shameful rout which for a long time was the basis of the belief throughout the South that one Southerner could whip four Northerners.