Complex sentence: He was re-elected after winning the five-way Republican primary outright, garnering seventy percent of the vote, thereby making history in South Carolina, as it was the first-five way primary where no run-off was needed.
Split into simpler sentences: He was re-elected after winning the five-way Republican primary outright, garnering seventy percent of the vote. This made history in South Carolina, as it was the first-five way primary where no run-off was needed.