Complex sentence: About 20 years ago, the citizens of The Republic had to search for a shelter from the hell of the Third World War, yet only a few were fortunate enough to have a place waiting for them in the prepared shelters.
Split into simpler sentences: About 20 years ago, the citizens of The Republic had to search for a shelter from the hell of the Third World War. Yet, only few were fortunate enough to have a place waiting for them in the prepared shelters.