Complex sentence: The retreat and the battle were rapidly perceived by the British public as being a key moment in the war, despite the censorship going on it was the first indication that defeating Germany would not be as easy as some had thought.
Split into simpler sentences: The retreat and the battle were rapidly perceived by the British public as being a key moment in the war. Despite the censorship going on it in Britain at the time, this battle was the first indication that defeating Germany would not be as easy as some had thought.