He was born on 8th July 1897 in Forni di Sopra, Udine, Italy the son of Siro Joseph and Luigia Dorigo Mannelli. His family moved to the United States when he was one year old, initially living in New York but moved to San Francisco in 1906.
His father was a Florentine sculptor who contributed to the Palace of Fine Arts for the Panama-Pacific International Exposition of 1915 as well as the Golden Gate International Exposition of 1939, both in San Francisco . The Golden Gate International Exposition was a World's Fair that celebrated, among other things, the city's two newly-built bridges. The San Francisco – Oakland Bay Bridge, which was dedicated in 1936 and the Golden Gate Bridge which was dedicated in 1937. During his career Siro won numerous awards for his sculpture and woodcarving.
Caesar was educated at Santa Clara University . Apart from rugby he was an excellent basketball player, but baseball was his best sport. He had a tryout with the minor league Oakland Oaks, but it was several years after his competitive prime and many people thought he could have played major league ball, had he started earlier. Mannelli later worked for the city of San Francisco as an engineer.
He played twice for the USA in the 1924 Olympics against Romania (won 37-0) and in the final against France when he scored, what would be, the last try in the Olympics for 92 years.
He died on May 3, 1936 in Antioch, CA.
Special thanks to The Rugby History Society for providing this bio.