 Complete the following phrase:  After the outbreak of the Greek War of Independence in March 1821, the Greeks captured the New Navarino fortress and slaughtered its garrison on the first week of August 1821. The area remained in Greek hands until 1825, when Ibrahim Pasha of Egypt captured the old castle on 29 April, followed by the fortress on 11 May. The Ottoman-Egyptian garrison remained there until it was handed over to the 