Complex sentence: Fourth-generation designs are heavily influenced by lessons learned from the previous generation of combat aircraft, long-range air-to-air missiles, originally thought to make dogfighting obsolete, proved less influential than expected precipitating a renewed emphasis on maneuverability.
Split into simpler sentences: Fourth-generation designs are heavily influenced by lessons learned from the previous generation of combat aircraft. Long-range air-to-air missiles, originally thought to make dogfighting obsolete, proved less influential than expected precipitating a renewed emphasis on maneuverability.