 At that time he also became a conscientious objector to the war in Europe, a political position that caused difficulties for him when he moved back to Berkeley following his graduation.Benson returned to Berkeley as an instructor in July 1942.In May 1946 he was invited to join the group of Melvin Calvin, who was then starting a photosynthesis group in Berkeley's Old Radiation Laboratory, a building that had previously housed a 37-inch cyclotron built in 1937 by Ernest Lawrence.