Complex sentence: In those 24 days of combat he became the first naval air ace of the battle and the highest scoring naval ace on the Supermarine Spitfire, a record which still stood by the end of the war.
Split into simpler sentences: In those 24 days of combat he became the first naval air ace of the battle and the highest scoring naval ace on the Supermarine Spitfire. A record which still stood by the end of the war.