Moss was born probably in Buckingham County where local tradition is that he was a member of the free African American Moss family. The destruction in 1869 of virtually all the county’s records makes it impossible to trace his early life. The names of his parents are not known, nor are the dates of his birth and death. The census enumerator in 1870 recorded Moss’s age as forty-five, and the enumerator in 1880 recorded his age as fifty-seven, indicating that he was born sometime in the mid-1820s. Moss’s name does not appear in pre-1870 census returns or in the land or personal property tax lists of Buckingham County before the end of slavery. That suggests but does not prove that he was born enslaved. John M. Schofield, the army general in control of Virginia as commander of the First Military District, recorded late in 1867 or early in 1868 that Moss had been born into slavery. An early 1869 notation in the records of the Bureau of Refugees, Freedmen, and Abandoned Lands (better known as the Freedmen’s Bureau) identified him as a freedman, while an 1874 newspaper paraphrase of a speech Moss made indicated that he stated that he had been enslaved.
Moss and his wife Amanda (birth name unrecorded) had at least four sons and one daughter. Contemporary newspaper descriptions of him suggest that he had a very dark complexion, and several unfriendly newspaper reports in the 1870s compared him to an elephant or hippopotamus, which may indicate that he was of large stature or obese. Moss was almost certainly literate by the time he entered politics. Insofar as is verifiable, he owned no real estate before February 4, 1871, when he purchased 25 acres of land for $55. Four years later Moss purchased 125 acres of land in the same part of the county for $450. He sold the 25-acre tract for $75 in 1877.
On October 22, 1867, when African Americans voted for the first time in Virginia, Moss won election to represent Buckingham County in the convention that met in Richmond from December 3, 1867, to April 17, 1868, to write a new state constitution. He received 1,535 votes, all from African American men, against a field of other candidates who together received a total of 1,097 votes, almost all from white men. Moss failed to take his certificate of election with him when he went to Richmond, but the delegates seated him on the authority of the tabulation that General Schofield had compiled officially reporting the results of the election.
One of two dozen African American delegates, Moss was appointed to the relatively unimportant Committee on Limitations and Guarantees. He voted with the radical reformers on every major issue. Schofield described him as “energetic and enterprising.” On January 28, 1868, in Moss’s only extended remarks, he opposed a proposal to exempt land from taxation, which some delegates, probably themselves landowners, stated would enable owners of land to hire more workers. Moss described himself as “a working man” and a representative of “the whole class of colored people in this State” and praised land ownership as a boon to freed people. He concluded, “When we get the land, notwithstanding the burthens of taxation may be upon it, we would—or at least I would—rather pay a high tax upon land and work it myself than to work for other people for nothing.” A hostile local white man not long thereafter dubbed him “Francis-Forty-Acre-and-a-Mule Moss.”
Early in September 1868 Freedmen’s Bureau officers ordered Moss arrested on a charge of “using in public speeches, language calculated to produce breach of the Peace, and also cause alienation and discord between White and Colored Citizens of Buckingham Co.” They evidently allowed him to remain at large, and early in January dropped the charge as false.
When voters ratified the new state constitution on July 6, 1869, Moss won election to the Senate of Virginia from the district consisting of the counties of Appomattox and Buckingham. He narrowly defeated white Conservative Party candidate George J. Hundley by 25 votes out of 4,279 cast. Moss was not appointed to any of the senate’s standing committees. In the short October 1869 session of the assembly he voted with the majority to ratify the Fourteenth and Fifteenth amendments to the Constitution as Congress required before it seated senators and representatives elected from the state. During the remaining three sessions, which concluded at the end of March 1871, the assembly made major revisions to the state’s laws to bring them into conformity with the new constitution. Among the most important of them was the 1870 law that created the state’s first (racially segregated) public school system for all children. After voting twice to strike racial segregation from the bill, he and two other African American senators did not vote on the final passage of the bill. Among the most controversial laws was the Funding Act of 1871, which provided for paying the prewar public debt. Along with most other African Americans in the assembly, Moss voted for it.
Moss was active in radical politics and was a delegate to the Republican Party state conventions in November 1869, when he served on the resolutions committee, and in September 1870. The new constitution set senators’ terms of office at four years but provided that half the senators elected in 1869 serve two-year terms in order that thereafter half the senators be elected every second year. Moss had to run for reelection in 1871. He lost to Hundley 2,673 to 2,351 in the reconfigured district that included Appomattox, Buckingham, and Fluvanna counties. One reason may have been Moss’s advocacy of racially integrated public schools.
In May 1872 Moss was elected to a one-year term on Buckingham’s board of supervisors. In July he delivered the fourth of July oration at a well-attended barbecue near the courthouse, and several reports of his participation in local politics appeared in newspapers published in distant cities. He became a member of the Republican Party state central committee in the spring of 1873 and attended the state convention that July. He was one of several prominent Republicans who refused to support the party’s nominee for governor. That and Moss’s general behavior had earned him a reputation for independence and divisiveness. Hostile white politicians and journalists repeatedly asserted that he advocated interracial marriage. A local white observer nevertheless reported that Moss deserved “more credit than all the white Radicals, because he has stuck to his color with indomitable pluck, and he carries the whole set his own way, and makes them vote for him to a man.”
That autumn Moss campaigned as a radical Republican and in November 1873, by a margin of 1,239 to 1,195, won election to the House of Delegates for a two-year term representing Buckingham County. A week after the election the county grand jury indicted Moss and two other men for assaulting a black man who had reportedly voted against him. One newspaper account stated that Moss beat the man severely. Released on $100 bail, Moss was tried in December, but the jury could not reach a verdict, and the commonwealth’s attorney dropped the charges in January when Moss was serving in the General Assembly.
In the 1874 session Moss was appointed to a low-ranking seat on the Committee on Labor and Poor and to the lowest-ranking seat on the Committee on Manufactures and Mechanic Arts. The Richmond Daily Whig reported that when Moss was speaking about the public debt during debate on March 18, Harrison H. Riddleberger, later a member of the U.S. Senate, asked Moss to yield that he might introduce a resolution. Moss reportedly yielded, and Riddleberger moved that Moss be expelled “as a nuisance.” The paper reported that the motion received two votes, but a variant of the report published in the Alexandria Gazette on the same day stated that it received four votes. The official published journal does not record Riddleberger’s making any motion at all relating to Moss.
In April 1875 Moss and twenty-one other men signed a call for a convention of African American men to organize a statewide effort on behalf of African Americans independent of white Republican leaders. By then the Republicans of Buckingham County were severely divided, and in the election for commonwealth’s attorney that spring Moss spoke out against the Republican incumbent who had prosecuted him for assault in the winter of 1873–1874. The National Republican, a Washington, D.C., newspaper that regularly reported on Virginia politics, denounced Moss in June 1875 as an offensive laughingstock. That November he lost his seat in the House of Delegates in a three-person race, receiving 706 votes out of 2,389 cast.
In the spring of 1873 Moss obtained a license to sell alcohol in the county and on September 10, 1878, a license to perform marriages. He remained active in local Republican Party affairs but evidently did not again run for office. By August 1880 Moss was supporting the biracial Readjuster coalition that proposed to reduce payments on the pre–Civil War public debt in order to increase appropriations for the public schools. His support of the Readjusters provided evidence to their opponents of how dangerous the Readjusters were.
Moss was still a divisive political leader, and for decades after his death white Virginians publicly demonized Moss and other outspoken African American politicians to validate white supremacy at the ballot box. In November 1883 he was secretary of a meeting of Buckingham County Republicans who opposed William Mahone, the Readjuster leader who was then serving as a Republican member of the U.S. Senate. A local white man in a speech in Staunton on August 6, 1884, stated that Frank Moss had died since speaking at an earlier meeting in Buckingham, but public records do not contain the date or circumstances of Moss’s death. He was most likely buried in a grave now unmarked on land his descendants owned near Jerusalem Baptist Church in Buckingham County.