Dear Mr. Dichtel,
Thank you for posting your request on History Hub!
We located a reference to the event you describe in The Times-Picayune, New Orleans, Louisiana 21 Apr 1843. Based on our reading of the article, this is not describing the formation of a new unit. Rather, this is referring to the meeting of the officers of an existing unit of the Louisiana Militia to elect regimental officers. In many militia units throughout the 18th and 19th century, officers were elected to fixed terms by members of their units, rather than being appointed by central authorities. In some cases, officers were elected every year. Furthermore, there is no indication this was connected to the Mexican War, which would not occur for another 3 years. The annexation of Texas and the subsequent border dispute between the US and Mexico which prompted the war would not occur for another 2 years. Rather, this appears to be a routine, peacetime activity. The National Archives does not keep records of peacetime state militia units. Please contact the Louisiana State Archives for information about militia records from this time period.
Should you have questions about the military records in National Archives custody relating to the Mexican War, 1846-1848, please contact the National Archives at Washington, DC - Textual Reference (RDT1) at Archives1reference@nara.gov.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT1. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this information is helpful. Best of luck with your research!