Complex sentence: The first president was Habib Bourguiba, who effectively led Tunisia from 1956 as the leader of the ruling party, who served as president from 1959 until a coup d'état in 1987, during which he was declared medically unfit to perform his duties.
Split into simpler sentences: The first president was Habib Bourguiba, who served as president from 1959 after effectively serving as the country's leader from 1956. He was removed from office in a coup d'état in 1987, during which he was declared medically unfit to perform his duties.