The 14th amendment was a part of the Reconstruction after the Civil War ended on May 9th, 1865. The 14th Amendment was needed because after the Civil War was over and slavery ended some southern states passed laws that restricted the rights of former slaves.
Because of that, the 14th Amendment was designed to protect those former slaves' rights and the only way southern states could be readmitted to the Union was ratifying the 14th Amendment.
That Amendment gives citizenship to all people born in the US or naturalized, with that, the federal government removed a series of powers some states had to supersede federal laws.
