Complex sentence: On 13 February 1943, the Squadron took off for a mission across northern France and shortly after crossing the French coast the Spitfires sighted and engaged a force of FW 190's.
Split into simpler sentences: On 13 February 1943, the Squadron took off for a mission across northern France. Shortly after crossing the French coast the Spitfires sighted and engaged a force of FW 190's.