The express purpose of the Northern invasion and occupation of Louisiana in 1862 was to forcibly hold the State in the Northern union, and through the imposition of a military-directed civil government. Despite the State already having a freely-elected legislature and governor, the Northern Congress proclaimed them criminals and supervised the establishment of a new administration under military control. The Michael Hahn mentioned below was a German immigrant to New York and then Texas, and a prewar import to Louisiana.
Bernhard Thuersam, Chairman
North Carolina War Between the States Sesquicentennial Commission
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Experimenting with Federally-Occupied State Governments
"Louisiana's situation was particularly bad because from the time that General Benjamin F. Butler and his troops came to New Orleans on May 1, 1862, south Louisiana was lost to the Confederacy. The loss of control of the Mississippi River isolated most of Louisiana and Texas. And while the war was going on in other places the Federal government was already experimenting with the "redemption" of Louisianians.
By January, 1864, Federal forces occupying Louisiana were intent upon effecting a civil government through which they could enact laws and render conditions amicable to their interests. On January 11, General N.P. Banks issued a proclamation ordering an election of State officials in federally-occupied Louisiana. By "federally-occupied," he acknowledged the division within the State.
In the meantime, Governor [Thomas O.] Moore delivered his farewell address, and on January 25 Henry Watkins Allen was inaugurated . . . governor of Louisiana. On March 4, Michael Hahn was inaugurated governor of Federal Louisiana . . . [and] the reality of two State administrations was a source of despair [for Louisianians].
The Union army captured Fort DeRussey and the interior of Alexandria and Natchitoches in March of 1864. A convention was held in New Orleans of April 6 to draft a constitution for federally-occupied Louisiana . . . [and on] July 23, 1864, a Republican convention revised the constitution and abolished slavery. On October 12, a resolution of [the US] Congress ordered the attorney general to institute criminal proceedings against all members of the 1860 Louisiana legislature who had voted for the Convention of Secession.
O June 2, 1865, Governor Allen delivered a farewell proclamation to the people of Louisiana and went into exile in Mexico . . . "
(Louisiana Legacy, A History of the State National Guard, Evans C. Casso, Pelican Publishing, 1976, pp. 83-85)