Dear Ms. Johnston,
Thank you for posting your request on History Hub!
The CMSR citation 8242-C-1886 refers to documents in Letters Received, 1862 - 1889 in the Records of the Adjutant General's Office, 1762 -1917 (Record Group 94). R&P refers to the Record and Pension Office. These records are not available online. For more information, please email 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 is helpful. Best of luck with your research!