sentences:  By this time the population of Thassos had gravitated to the inland villages as a protective measure.Nearly 50 years later, a revolt against Ottoman rule arose in 1821, at the outbreak of the Greek War of Independence, led by Hatzigiorgis Metaxas, but it failed.The island had been given in 1813 by the Sultan Mahmud II to Muhammad Ali of Egypt as a personal fiefdom, as a reward for his intervention against the Wahhabites.