| Name | Date of Rank | Date of Commission |
| Charles W. Long, Captain | 26 June 1862 | 18 July 1862 |
| George W. , First Lieutenant | 26 June 1862 | 18 July 1862 |
| Amos Hansell, Captain | 1 July 1863 | 19 August 1863 |
| James C. Parker, First Lieutenant | 1 July 1863 | 19 August 1863 |
For a number of years, the district lying between the border of Humboldt and Trinity Counties had been infested by hostile bands of Indians who had manifested their hostility by repeated outrages against the lives. and property of the citizens of those counties. The regular United States military authorities had been appealed to for aid, but they failed to afford any efficient assistance. The citizens, therefore, appealed to the Governor of the State to organize volunteer military companies under the command of competent officers, for the purpose of subduing these Indians, and affording protection to the citizens of Humboldt County.
The Eureka Rifles, under the command of Captain Charles Long, was one of the many companies organized in Humboldt County to check the Indian depredations. This company was composed of forty well trained men, and although there was only a meager source of information concerning their activities, it is assumed that the Eureka Rifles during their existence aided materially to bring peace to Humboldt County.
Upon the recommendation of Adjutant General George S. Evans, the Eureka Rifles were mustered out of the service of the State of California July 6, 1864.