Complex sentence: It was written in memory of Greg Carroll, a Māori the band met in 1984 during The Unforgettable Fire Tour who later became close friends with lead singer Bono and served as a roadie for the group.
Split into simpler sentences: It was written in memory of Greg Carroll, a Māori the band met during The Unforgettable Fire Tour in 1984. He became very close friends with lead singer Bono and served as a roadie for the group.