sentences:  The 447th's first mission from Rattlesden was despatched on Christmas Eve and, during the course of hostilities, another 256 missions were flown from the base.The group helped to prepare for the invasion of the Continent by attacking submarine pens, naval installations, and cities in Germany; ports and missile sites in France, and airfields and marshalling yards in France, Belgium, and Germany.During Big Week, 20–25 February 1944, the 447th took part in the intensive campaign of heavy bombers against the German aircraft industry.