The U.S government militarized the South because they wanted to oversee the election and registration of voters. Only after new state constitutions had been written and states had ratified the Fourteenth Amendment could these states rejoin the Union. Predictably, President Johnson vetoed the Reconstruction Acts, viewing them as both unnecessary and unconstitutional. Once again, Congress overrode Johnson’s vetoes, and by the end of 1870, all the southern states under military rule had ratified the Fourteenth Amendment and been restored to the Union.