Complex sentence: When Curtis left the group to join the air force in 1955, he was replaced by Milton Love (formerly of the Concords), and it was with Love that the Solitaires enjoyed their greatest success.
Split into simpler sentences: When Curtis left the group to join the air force in 1955, he was replaced by Milton Love (formerly of the Concords). It was with Love that the Solitaires enjoyed their greatest success.