Complex sentence: Both the Aden naval base and the Suez Canal itself were closed in the same year, and the Canal--shut by Nasser on the eve of war with Israel--would remain closed until 1975.
Split into simpler sentences: Both the Aden naval base and the Suez Canal itself were closed in the same year. The Canal--shut by Nasser on the eve of war with Israel--would remain closed until 1975.