Dear Ms. Holden,
Thank you for posting your question on History Hub!
The information you are seeking might be in his Official Military Personnel File (OMPF). Official Military Personnel Files (OMPFs) and medical records of officers and enlisted personnel of the U.S. Marine Corps who were separated from service after 1904 and prior to 1957 are located at NARA's National Personnel Records Center (NPRC), (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. To request these records, please mail a completed GSA Standard Form 180 to NPRC. Or you may apply online at https://www.archives.gov/veterans/military-service-records/.
We hope this information is helpful. Best of luck with your family research!