Dear Mr. Hohman,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located 11 record series in the Records of U.S. Regular Army Mobile Units (Record Group 391) created by the 4th Cavalry Regiment during the 1860s, including Returns, 1860 - 1918. We also located Duplicate Copies of Post Returns, ca. 1866 - ca. 1909 and Returns of Military Organizations, 1800 - 12/1916 in the Records of the Adjutant General's Office, 1762 - 1917 (Record Group 94) that may include copies of the returns you are seeking. For more information about these records, please contact the National Archives at Washington, DC - Textual Reference (RDT1) 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 RDT1. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your research!