Dear Ms. Heinzman,
Thank you for posting your inquiry on History Hub!
We searched the National Archives Catalog and located the series titled World War II Operations Reports, 1940-1948 in the Records of the Adjutant General's Office, 1917 - 1981 (Record Group 407) that may contain records of the 156th Infantry Regiment. For more information about these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
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 RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
Since the 156th Infantry Regiment was initially part of the Louisiana National Guard, the Louisiana State Archives may have additional records concerning the unit. Finally, you may also wish to contact the Louisiana National Guard Museums, the State Library of Louisiana, and the National World War II Museum.
We hope this is helpful. Best of luck with your family research!
Here is some information below. Regarding the split of the Unit.
25 Nov 40 inducted into federal service at New Orleans LA assigned to the 31st Division and moved to Camp Blanding Fla 22 Dec 40; transferred to Camp Bowie TX 26 Feb 42 where relieved from the 31st Division on 14 July 42; staged at Ft Dix NJ 19 Sep 42 until departed NY 26 Sep 42; arrived in England 6 Oct 42 and 2nd Bn sent to Oran Algeria for military police duties due to its French linguistic ability where it later was re-designated the 202nd Infantry Battalion; regiment assigned to the US Army Assault Training Center at Woolacombe England in July 43 and new 2nd Bn formed from the 3rd Bn, 131st Infantry Regiment; headquarters detachment and Co L assaulted Normandy France on 6 June 44 and entire regiment ashore by 24 June 44; returned to England 6 July 44 and returned to France by echelon 18 Aug-3 Sep 44; guarded flanks of allied advance and Red Ball Express highway; 2nd Bn detached to guard Supreme Headquarters Allied Expeditionary Force Headquarters from 15 Oct 44; remainder of regiment moved in mid-Nov 44 to provide security duty at the US Embassy, US Naval Headquarters and other command facilities in Paris; regiment, less 2nd Bn, moved to Normandy coast in mid-Dec 44 where contained German garrisons on the Channel Islands; returned to NY 11 Mar 46 and inactivated at Camp Kilmer NY on 13 Mar 46.