In the mid-450s the Athenians launched an unsuccessful attempt to aid an Egyptian revolt against Persia, which led to a prolonged siege of a Persian fortress in the Nile Delta. The campaign culminated in disaster; the besieging force was defeated and destroyed. In 451–450 BC the Athenians sent troops to Cyprus. Cimon defeated the Persians in the Battle of Salamis-in-Cyprus, but died of disease in 449 BC. Pericles is said to have initiated both expeditions in Egypt and Cyprus, although some researchers, such as Karl Julius Beloch, argue that the dispatch of such a great fleet conforms with the spirit of Cimon's policy.