Returning to Dover, he continued the study of law—which he had commenced in New York—in the office of the eminent lawyer, Daniel M. Christie, and on that gentleman's motion was admitted to the bar at the May term, 1860. He afterwards well repaid Mr. Christie's kindness by a eulogy, upon his decease, delivered before the court, and subsequently printed. It was regarded as an eloquent and appreciative tribute to Mr. Christie's remarkable qualities of manhood, and extraordinary powers as a lawyer.
Mr. Hall, upon his admission to the bar, opened an office in Dover, and commenced practice. In the spring of 1859, just before the state election, in view of the great crisis coming upon the country, at an immense meeting in Dover, he (as did also Judge Charles Doe) withdrew from the Democratic party and cast in his allegiance with the Republicans. With them, where his conscience and political principles alike placed him, has his lot been cast ever since; and it is not improbable that that one addition, in later and critical years, turned the scale in New Hampshire's political destinies.
It was an episode in his life that in 1859 he was appointed, by the governor and council, school commissioner for Strafford county, and re-appointed in 1860. His early training in the country district school, his work as master in the winters, and his hard-earned higher education qualified him eminently for the practical duties of this office.
In the autumn of 1861, Mr. Hall was appointed secretary of the United States senate committee to investigate the surrender of the Norfolk navy-yard. This committee consisted of John P. Hale, Andrew Johnson, and James W. Grimes. Soon after, he was appointed clerk of the senate committee on Naval Affairs, at Washington, of which Mr. Hale was chairman. He served in this capacity until March, 1862; but he wished for more immediate participation in the great struggle then in progress. The conflict, which had its symptoms in the Lecompton strife, had become war, and the young man who had then sacrificed office for principle was ready for a still greater sacrifice. In March, 1862, he was commissioned aid-de-camp and captain in the regular army of the United States. He was assigned to duty with Gen. John C. Fremont; but before he had time to join that officer, Gen. Fremont had retired from command, and Capt. Hall was transferred to the staff of Gen. A. W. Whipple, then in command at Arlington Heights, of the troops and works in front of Washington, on the south side of the Potomac. In September, 1862, a few days after the battle of Antietam, Gen. Whipple joined the army of the Potomac, and eventually marched with it to the front of Fredericksburg. On the 13th of December, 1862, he was in the battle of Fredericksburg, crossing the river with the third corps, and taking part in the sanguinary assault upon the works which covered Marye's Heights.
At the battle of Chancellorsville he was in the column sent out to cut Jackson's line as he moved in front of the army, and in the gallant action of the third division of the third corps, under Gen. Whipple, of whose staff he was a member, and was with that lamented officer when he fell mortally wounded. Capt. Hall was then assigned to the staff of Gen. Oliver O. Howard, commander of the eleventh corps, and with him went to Gettysburg. His position in that action was important. When Gen. Reynolds, commanding the first corps, had advanced through the town and encountered the enemy, Gen. Howard, then moving up and about five miles to the rear, hearing the heavy firing, ordered Capt. Hall to ride forward as rapidly as possible, find Gen. Reynolds, ascertain the condition of affairs, and obtain his orders. Capt. Hall's fleet horse soon covered the distance, and he found Gen. Reynolds himself in an advanced and exposed position from the enemy's fire. He did his errand; Gen. Reynolds said he had met the enemy in force, and sent the order to Gen. Howard to bring up his corps with all possible dispatch. Scarcely had Capt. Hall got back through the town, when he was overtaken by the intelligence that Gen. Reynolds was mortally wounded, and near the cemetery he met Gen. Howard impatiently coming up in advance of his corps. Passing Cemetery Ridge, Gen. Howard said, "That is the place to fight this battle," and directed Capt. Hall to take a battery from the leading division, and place it in position on the crest of the hill. This was done, and that battery, the first planted on Cemetery Hill, remained on that spot through the three days of the conflict. When Gen. Howard took his own place there, Capt. Hall was of course with him, and on the second day of the engagement was slightly wounded by a shell. These details are given, simply to place on record, in this permanent form, his testimony to the justice of the claim made by the friends of Gen. Howard, that he was fully entitled to the thanks voted him by congress for selecting Cemetery Hill and holding it as the battleground of the great and glorious battle of Gettysburg.
In the latter part of 1863 his health suffered, and he was forced to leave the service in December, 1863. But in June, 1864, he was appointed provost-marshal of the first New Hampshire district, being stationed at Portsmouth, and here he remained until the close of the war. The affairs of the office were in some confusion, but his methodical habits soon reduced it to order. During his term of service, he enlisted or drafted, and forwarded, over four thousand men to the army. This service ceased in October, 1865. "He was one of the men," said a substitute broker to the writer of this sketch, "that no man dared approach with a crooked proposition, no matter how much was in it."
Mr. Hall resumed the practice of law in Dover, but in 1866 was appointed clerk of the supreme court for Strafford county, and in 1868, judge of the police court of the city of Dover. The duties of these offices were performed with his usual sense of justice, but in 1874, the Democratic party, being in power, "addressed" him out of both offices. In the mean time he had been judge-advocate, with the rank of major, in the military of New Hampshire, under Gov. Smyth, and held a position on the staff of Gov. Harriman, which gave him his usual title of Colonel.
Col. Hall had long taken a deep interest in political affairs. To him they represented principles. In 1873 he was president of the Republican state convention at Concord. He had been for some years a member of the Republican state committee, when, in December, 1873, his abilities as a leader and executive were recognized in his selection as chairman of that committee. He so remained until 1877, and conducted the campaigns, state and national, of 1874, 1875, and 1876. These were critical years for the Republican party. The nearly even balance of parties in New Hampshire, the vigor and intensity with which the battles are always fought, and the skill necessary in every department, demand abilities and energies of the highest order. The years mentioned surpassed ordinary years in political danger to the Republicans. It is sufficient to say that Col. Hall conducted the last three campaigns to a triumphant issue. So decisive were the successive victories that the tide was turned, and from that time the state has not swerved from Republican allegiance.
In 1876, Col. Hall was chairman of the New Hampshire delegation to the Republican national convention at Cincinnati, being chosen at large, unpledged, and with scarce a dissenting vote. Seven delegates voted from first to last for James G. Blaine; but Col. Hall, with ex-Gov. Straw and Hon. Charles H. Burns, voted six times for Mr. Bristow, and on the decisive ballot for Rutherford B. Hayes.
In 1876 and 1877, Mr. Hall was, by appointment of Gov. Cheney, reporter of the decisions of the supreme court of New Hampshire, and in that honorable position published vols. 56 and 57, New Hampshire Reports.