[Source: Descriptive Rolls of 91st PA; National Archives and Record Administration]
[related page: officers in the 91st PA (Official Army Register)
List of Commissioned Officers.
| No. | Names | Rank | Date of Appointment. | Remarks. |
| 1 | F. B. Gilbert | Captain | Sept 30th 1861. | Resigned [?--it's very light] |
| 1 | F. H. Gregory | 1st Lieut | Sept 2d " | promoted to Capt. Jany 18th /63 |
| 1 | Ansel Hamberg | 2d Lieut | Sept 30th " | Resigned June 3d 1862 |
| Randolph M Smith | 2 " | June 12 /62 ['June' seems to be written over 'Jany'; the '1' in the date is unclear] | " Dec 10 1862 | |
| John G Brass | 2 " | Dec 10th [?] / 62 | as 2d Lieut. promoted to 1st Lieut |