Answer:
In 1956, Adlai Stevenson replaced J.E. Hill as an advisor. Adlai Stevenson was a prominent figure in American politics at that time.
Step-by-step explanation:
He had previously served as the governor of Illinois and was the Democratic Party's nominee for president in both 1952 and 1956. After his time as an advisor, Stevenson went on to serve as the United States ambassador to the United Nations. His role as an advisor marked an important transition in the political landscape of that era.