The following year the Greek cause indirectly suffered a great blow by the capture and death of Ali Pasha. This ambitious and daring rebel, from humble origin, had arisen, by energy, ability, and fraud, to a high command under the Sultan. He became pasha of Thessaly; and having accumulated great riches by extortion and oppression, he bought the pashalic of Jannina, in one of the richest and most beautiful valleys of Epirus. In the centre of a lake he built an impregnable fortress, collected a large body of Albanian troops, and soon became master of the whole province. He preserved an apparent neutrality between the Sultan and the rebellious Greeks, whom, however, he secretly encouraged. In his castle at Jannina he meditated extensive conquests and independence of the Porte. At one time he had eighty thousand half-disciplined Albanians under his command. The Sultan, at last suspecting his treachery, summoned him to Constantinople, and on his refusal to appear, denounced him as a rebel, and sent Chourchid Pasha, one of his ablest generals, with forty thousand troops, to subdue him. This was no easy task; and for two years, before the Greek revolution broke out, Ali had maintained his independence. At last he found himself besieged in his island castle, impregnable against assault, but short of provisions. From this retreat he was decoyed by consummate art to the mainland, to meet the Turkish general, who promised an important command and a high rank in the Turkish service. In the power now of the Turks, he was at once beheaded, and his head sent to Constantinople.