In three days after the receipt of the startling intelligence that the Stars and Stripes had been fired upon by rebels in arms, PITTENGER was on his way to the Capital as a private soldier in the Second Ohio Regiment of volunteers. He fought bravely on the disastrous 21st of July, in the battle of Bull Run, while many of his comrades fell bleeding at his side. For his calm, heroic conduct throughout that memorable day of peril and panic, he received the highest praise from every officer of his regiment. Although thus a sharer of war's sternest conflicts during the three months' campaign, he was ready to re-enlist immediately, when his country called for a longer service; and after a few days' rest beneath the old homestead roof, he was again on his way with the same regiment to the seat of war in the Southwest. During the fall and winter he saw severe service on the "dark and bloody ground." No soldiers ever endured so many midnight marches more patiently, or manifested more self-sacrificing devotion to country, through rains and storms, and wintry desolations, than the noble Ohio Second, under the command of Colonel HARRIS, through the campaign in the mountains of eastern Kentucky. In December, the regiment was transferred to the Division commanded by the lamented General MITCHEL, then encamped at Louisville. From this point, the army pressed forward victoriously through Elizabethtown, Bowling Green, Nashville, and Murfreesboro', until the old banner floated in the Tennessee breezes at Shelbyville. While here, the daring expedition to penetrate the heart of the Confederacy was organized, of which party PITTENGER was one of the most enthusiastic and determined. From the day the brave fellows departed over the Southern hills on their adventurous journey, a veil was dropped which hid them from sight of friends for many weary months--and some of them for ever! No tidings came in answer to all the beseeching thought-questionings that followed their mysterious pathway "beyond the lines."