Under this plan, 10 percent of each state's population would have to swear an oath of allegiance, also known as an ironclad oath, and they would be required to adopt the 13th amendment into their state constitution. This amendment abolished slavery but didn't protect the rights of all people. So when Tennessee technically rejoined the Union, they weren't required to protect the rights of African-Americans. The extent to which the African-American population would be protected was left up to the local police and lawmakers. This was especially a problem in Memphis as the vast majority of the Memphis police force in the 1860's was Irish. Ryan, James Gilbert. "The Memphis Riots of 1866: Terror in a Black Community During Reconstruction". The Journal of Negro History 62.3 (1977): 243–257.