You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
North_Carolina

Context:
In 1860, North Carolina was a slave state, in which one-third of the population was enslaved. This was a smaller proportion than in many Southern states. The state did not vote to join the Confederacy until President Abraham Lincoln called on it to invade its sister state, South Carolina, becoming the last or second-to-last state to officially join the Confederacy. The title of "last to join the Confederacy" has been disputed; although Tennessee's informal secession on May 7, 1861, preceded North Carolina's official secession on May 20, the Tennessee legislature did not formally vote to secede until June 8, 1861.

Question:
North Carolina did not vote to join the confederacy until they were ordered to invade what state?

South Carolina