In May 1821, at the beginning of the Greek Revolution, the Greek rebels of Mount Pelion tried to capture the fortress but failed. On 8 April 1827, the Greek fleet, under the command of the British philhellene Frank Abney Hastings, captured five Ottoman ships in the city's harbour and forced the local garrison to evacuate the fortress. The provisional government of Greece claimed Volos as part of Greek national territory, but the Treaty of Constantinople (1832), which established a Greek independent state, set its northern boundary along a line running south from Arta to Volos. Volos was incorporated into the Greek Kingdom in November 1881 with the rest of Thessaly.