Complex sentence: Major General Carl Spaatz, head of the USAAF in Europe, wanted to spread the experience of the Eagles amongst various new US fighter squadrons but the pilots of the three Eagle Squadrons wanted to stay together.
Split into simpler sentences: Major General Carl Spaatz, head of the USAAF in Europe, wanted to spread the experience of the Eagles amongst various new US fighter squadrons. However, the pilots of the three Eagle Squadrons wanted to stay together.