During his study of the law he earned his livelihood by attention to the agency of real estate, with which he was intrusted, and by writing short articles for the press, for which he developed an early taste. His diploma admitted him to all the courts of the State, and he immediately commenced the practice of law, blending with this the duties of a notary public, receiving his commission in 1851.
When but twenty-two years of age he was elected a school director, and served on the committee on teachers with such men as Rawle, Jennings, and Bonford. This position he filled several times, and was at one time president of the board and ex officio chairman of the committee on teachers and high schools.
In politics Mr. Hahn was a Democrat and a member of the Douglas State committee, supporting Stephen A. Douglas for President. After the disruption of the Charleston convention he was pronounced in his attachment to the perpetuation of the Union, and when in 1861 all persons holding office were required by the Louisiana legislature to swear allegiance to the confederate government he declined.
On the arrival of Farragut and Butler at New Orleans Mr. Hahn was recognized as a Union man, and became prominent in devising means for the re-establishment of the State government within the lines of Federal control.
On the 3d of December, 1862, elections for Congress were held in the first and second districts of Louisiana, then entirely within the Federal lines. Mr. Hahn was elected in the second district, receiving more votes than his three competitors, Darrell, Greathouse, and Jacob Barker, together, but was not admitted to his seat until the 17th of February, 1863.
During his short stay in Congress he became an intimate friend of President Lincoln, whose confidence he enjoyed. During the year 1863 he was appointed and acted as prize commissioner at New Orleans. He was appointed by General Banks with two others commissioners to liquidate the affairs of the Bank of Louisiana; but on his recommendation the appointments were revoked and the bank allowed to settle its own affairs.
