History of the Peloponnesian War

The Lacedaemonians, when they found the war against those in Ithome prolonged, called other allies to their aid, and the Athenians also; who went under the command of Cimon with no small force.

They asked their aid, because they were considered to be skilful in conducting sieges: whereas in themselves, from the siege having been so protracted, there seemed to be a deficiency of this skill; for else they would have taken the place by assault.