In 1081 Alexios I Komnenos, in order to earn the support of Venice in the war against Normans, vested Venetians, by means of a chrysobull (golden bull), with a full tax-exemption for almost all the cities and mercantile stations of the empire. In the following years, he tried to create rivalry among the Italian cities whose power had started to rise dangerously, by ceding similar privileges to other cities also: first to Pisa (1111) and later to Genoa(1155). These privileges reduced the yield of the kommerkia, namely of the diapylia and diagogia dues imposed by the Byzantine government on merchants, resulting in a decrease in state revenues. Towards the end of the 12th century, several thousand Latins lived inside Constantinople exploiting the trade advantages of the city to its full but yielding no profit to the Byzantine state. The Byzantine reaction broke out in 1183 during the reign of Andronikos I Komnenos with wholesale pillaging and massacres of the Italians in all the cities of the empire. For a short period of time all commercial privileges were cancelled. The problem was solved for once and for all when the Western Europeans embarked on the Fourth Crusade and dissolved the Byzantine state in 1204.