The 51st Infantry Division "Siena" (Italian: 51ª Divisione di fanteria "Siena") was an infantry division of the Royal Italian Army during World War II. The Siena was formed on 15 September 1939 and named for the city of Siena. The division was a Campanian unit and it's men were almost entirely from Naples. After fighting in the Greco-Italian War the division was sent to Crete as garrison unit. There the division was disbanded by invading German forces after the Armistice of Cassibile was announced on 8 September 1943.