It has everything to do with immigration. The citizenship of native born white children was settled in 1802 regardless of the country of origin of their parents. The 14th amendment extended that to all people born on US soil.
Not in the original intent as there were no immigration laws at the time, as you pointed out.
https://usconstitution.net/constamnotes.html
13th Amendment
Slavery was an institution in America in the 18th and 19th centuries. The Southern states, with their agricultural economies, relied on the slavery system to ensure the cash crops (cotton, hemp, rice, indigo, and tobacco, primarily) were tended and cultivated. Slaves were not unknown in the North, but abolition in the North was completed by the 1830's. In 1808, the Congress prohibited the slave trade, not a year later than allowed in the Constitution. A series of compromises, laws, acts, and bills tried to keep the balance between the slave states and the non-slave states. For a more thorough history of slavery, see the
Slavery Topic Page.
South Carolina voted to secede from the United States as a result of Abraham Lincoln's election to the Presidency. Lincoln had, over time, voiced strong objections to slavery, and his incoming administration was viewed as a threat to the right of the states to keep their institutions, particularly that of slavery, the business of the states. More states seceded, eleven in all, forming the Confederate States of America. The secession movement led to the Civil War. In the waning days of the war, which ran from 1861 to 1865, the Congress approved an amendment to abolish slavery in all of the United States. Once the CSA was defeated, approval of the
13th Amendment was quick in the Northern states. By the end of 1865, eight of the eleven Confederate states had also ratified it. Proposed on January 31, 1865, it was ratified on December 6, 1865 (309 days). Eventually, all of the CSA states except Mississippi ratified the 13th after the war; Mississippi ratified the amendment in 1995.
14th Amendment
The ratification of the 13th Amendment was a major victory for the North, and it was hoped that with the
Emancipation Proclamation and the 13th Amendment, the effects of slavery in the United States would quickly diminish. The original plan to readmit states after acceptance of the 13th was supported by President Andrew Johnson, but the Radical Republicans, as they became known, wanted more than just a return to normalcy. They wanted to keep the power they had attained during the war years. The South did not make it easy for Johnson, however, and the so-called Black Codes started to be passed in Southern states. Congressional inquiries into the Black Codes found them to be a new way of controlling ex-slaves, fraught with violence and cruelty.
The ensuing Reconstruction Acts placed the former CSA states under military rule, and prohibited their congressmen's readmittance to Congress until after several steps had been taken, including the approval of the
14th Amendment. The 14th was designed to ensure that all former slaves were granted automatic United States citizenship, and that they would have all the rights and privileges as any other citizen. The amendment passed Congress on June 13, 1866, and was ratified on July 9, 1868 (757 days).
15th Amendment
The last of the Reconstruction Amendments, the
15th Amendment was designed to close the last loophole in the establishment of civil rights for newly-freed black slaves. It ensured that a person's race, color, or prior history as a slave could not be used to bar that person from voting. Though a noble idea, it had little practical effect for quite some time, as the Southern states found myriad ways to intimidate blacks to keep them from voting. The Congress passed the amendment on February 26, 1869, and it was ratified on February 3, 1870 (342 days).
Though ratification of the 15th Amendment was not a requirement for readmittance of the Confederate states to the Congress, one of the provisions of the Reconstruction Acts required that the states include a provision in their new constitutions that included a near-copy of the text of the 15th. All of the CSA states except Tennessee, which was immune from the Reconstruction Acts, eventually ratified the 15th Amendment.