After the British lost the Battle of Britain and the British Isles where invaded by the German army, the U.S. Army Air Corps knew they would need a long-range escort fighter.  To escort the new B-29 bombers from Iceland to Berlin.  So, they combined the two best fighters in the Air Corps inventory.  They put together the P-47 Forked Lighting from the P-38 Lighting and the P-51 Mustang.  The P-47 and the Twin Spitfire eventually swept the European skies clean of German fighters.

Halsted