His work in Florence was interrupted during World War II when he was imprisoned in an Italian fascist concentration camp in 1944–1945.
His most successful pieces were his requiem Missa pro defunctis and his mass Sette variazioni sopra una sarabanda di Corelli.
After earning his diploma in violin in 1911,[1] he continued his studies at the conservatory in music composition under Ferruccio Busoni and Luigi Torchi.
During World War II, he was imprisoned in an Italian Fascist concentration camp in Collescipoli, Terni from December 1944 through August 1945.
He wrote in a style heavily influenced by Maurice Ravel and Richard Strauss in the early part of his career.
[2] Some of his better known works from this period are his tone poem L’ultimo viaggio d’Odisseo and his Sonata for violin and pianoforte, both composed in 1921.
[2] Guerrini's most successful pieces in his later career were his sacred works, including the requiem Missa pro defunctis for vocal soloists, chorus, and orchestra which he composed in 1938–1939; and the mass Sette variazioni sopra una sarabanda di Corelli (1940).
[2] Missa pro defunctis was written in honor of the Italian inventor Guglielmo Marconi and was premiered at the Teatro Comunale, Florence on April 28, 1942.