Berthold joined the infantry in 1910 and learned to fly during 1913. When the war began, he transferred to the German Air Service as an observer. In 1916, he began flying single-seat fighters with Kek Vaux and was credited with five victories before crashing a Pfalz E.IV on April 25, 1916.
He suffered several wounds and injuries during the war, but would return to active duty before he had fully recovered. In August, he formed Jasta 4 before turning command over to Hans Buddecke. Berthold then assumed command of Jasta 14 until he was badly wounded in May 1917 when his Pfalz D.III was shot down. Recovering from a broken nose, fractured skull, thigh and pelvis, he returned to duty the following August and assumed command of Jasta 18. He was wounded again on October 10, 1917 when a bullet fractured his right arm.
When he returned to duty, he assumed command of Jagdgeschwader 2, remaining in command until he was wounded on August 10, 1918. Credited with downing two D.H.4s that day, his fighting days ended when his badly damaged Fokker D.VII crashed into a house after colliding with his second opponent. He was killed by rioters in 1920, some claim Berthold that was strangled with the ribbon from his Blue Max medal.