Complex sentence: As the modern Italian battleships were then interned in the Great Bitter Lake, after the armistice between Italy and the Allies, a modern battleship was no more needed in the Mediterranean, thence "Richelieu" steered to Scapa Flow, arriving on 20 November.
Split into simpler sentences: As the modern Italian battleships were then interned in the Great Bitter Lake, after the armistice between Italy and the Allies, a modern battleship was no longer needed in the Mediterranean. Thence "Richelieu" steered to Scapa Flow, arriving on 20 November.