Complex sentence: Neddermeyer was replaced as head of the E- 5 Group by Kistiakowsky on June 15,1944, but remained a technical adviser to the implosion program, with group leader status.
Split into simpler sentences: Neddermeyer was replaced as head of the E- 5 Group by Kistiakowsky on June 15,1944. He remained a technical adviser to the implosion program, with group leader status.