Trying to understand what this record means from my great grandfather in army WWII

Wilson Thomas I Major Connecticut (accessed or lived there at time of enlistment/commissioning) Born in North Carolina 6 Sep 06 Air Medal with 4 Oak Leaf Clusters Graduate Field Artillery School Self Propelled (?) Battery Officer Course, 1943 Officer Advanced Course 1944 National Guard of the United States CAC? Promoted to Major 24 Sep 48 Orders Number 0384501 Enlisted 16 Oct 35 to 26 July 39  2LT Field Artillery, First Lietenant 21 Jan 41 to 20 Oct 45 (Not sure about the F-1 Notation, might be a code that indicates a change of commission status from NGUS to AUS Army of the United States (a designation  for a component of the United States Army, read the wiki article on AUS too long to explain here) AUS Rank Captain 17 Jul 41 to 7 Jan 46 Officers Reserve Corp FA Captain 21 Oct 45 to 20 Nov 47 Captain Coastal Artillery Command 16 Sep 47 then designated Major 26 Jul 48.     NOTE  You could be a Captain in  National Guard, get transferred out to a Regular Army Unit in a combat zone, get a temp promotion to MAJ  and revert back to your old rank of Captain after transferring back to your National Guard unit at wars end. Officer promotions in the Regular Army were done by Congress, in the National Guard each state handled their own. To equalize/normalize things you could get a temporary promotion to match what job position you were filling but your actual pay grade might stay at your permanent rank. Sometimes this was called a Brevet Promotion Hope this helps a bit  Greg

Thank you so much!!

Thank you. This was very helpful. I can't wait to show tell my mom and grandma! 

Incredible. Thank you for finding this!

Hello Emmagrace 

Thank you for posting your question on History Hub!

You may also want to request his Official Military Personnel File (OMPF) for additional information about his service. In general, OMPFs for military personnel who were separated from the service between 1912 and 1992 are in the custody of NARA's National Personnel Records Center (NPRC) in St. Louis. In many cases where personnel records were destroyed in the 1973 fire, proof of service can be provided from other records such as morning reports, payrolls, and military orders, and a certificate of military service will be issued.

For the location of all service records organized by branch and year, please see the following link: https://www.archives.gov/veterans/military-service-records/locations

Veterans and next of kin of deceased veterans may use eVetRecs to request records. See eVetRecs Help for instructions. Please note that next of kin of a deceased veteran must provide proof of death of the veteran such as a copy of death certificate, letter from funeral home, or published obituary. For more information see Request Military Service Records.

You may also complete a GSA Standard Form 180 and mail it to NARA's National Personnel Records Center, (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002.  If there is any information requested by the form that you do not know, you may omit it or provide estimates (such as for dates), but the more information you provide, the easier it will be to locate the correct file. For more information see Official Military Personnel Files (OMPF).

Archival OMPFs, those that are 62 years and older, may also be requested by visiting the Archival Research Room at the National Archives at St. Louis. Please email stlarr.archives@nara.gov for further assistance prior to making an appointment.

We hope this helps with your research!