The roots of Greek success in the Ottoman Empire can be traced to the Greek tradition of education and commerce. It was the wealth of the extensive merchant class that provided the material basis for the intellectual revival that was the prominent feature of Greek life in the half century and more leading to the outbreak of the Greek War of Independence in 1821. Not coincidentally, on the eve of 1821, the three most important centres of Greek learning were situated in Chios, Smyrna and Aivali, all three major centres of Greek commerce. Greek success was also favoured by Greek domination of the Christian Orthodox church.