Complex sentence: It took over twelve hours for the crew to contain and extinguish the fire, one of the largest non-combat fires aboard a U.S. Naval vessel since the devastating fire on board the in 1967.
Split into simpler sentences: It took over twelve hours for the ship's crew to contain and extinguish the fire. It was one of the largest non-combat fires aboard a U.S. Naval vessel since the devastating fire on board the in 1967.