From Constitution US

The 13th Amendment is about the abolition of slavery. The promise that slavery, or “involuntary servitude,” would exist no longer within the United States. The exception here is on the conviction of a crime. This amendment was ratified on December 6, 1865.

The 14th Amendment is the assertion that all those born or naturalized within the United States are citizens of the United States. Furthermore, the promise that no state will enforce any law that will damage these privileges in any way. This is also known as the Equal Protection Clause and was ratified on July 9, 1868.

The 15th Amendment stipulates that any citizen of the United States has the right to vote, regardless of their race and color of their skin. This constitutional amendment also mentions those with a “previous condition of servitude,” which grants the right to former slaves. It was ratified on February 3, 1870.

Essentially, these three amendments were passed after the South got their shit kicked in in the Civil War and guarantee that the US government can not be discriminate against someone based on race