As mentioned in a post below, the Archimedes novel The Sand-Reckoner by Gillian Bradshaw it set in the time of the first siege of Syracuse, during the First Punic War. Although the conflict was between Rome and Carthage, Syracuse was drawn into it.
Most of what we know about the war comes from Polybius. He can be read both at livius.org: First Punic War and at LacusCurtius, Polybius: The Histories.
This informative page, First Punic War, comes from Wikipedia (as usual handle with care).
First Punic War between Rome and Carthage
(Ancient/Classical History at About.com)
Theodor Mommsen: The History of Rome, Chapter II
The War Between Rome and Carthage, Concerning Sicily
Recent treatments:
The Punic Wars by Adrian Goldsworthy (2002)
The First Punic War, A Military History by J.F. Lazenby (1996)
