Up to 1204 the Black Sea remained for foreign merchant fleets a more or less closed basin, effectively controlled by the Byzantine Empire at the straits and on the Bosphorus. Occasionally military conflicts or assaults, such as the Russian attacks on Constantinople and the Byzantine shores in 860, 907 and 941, could alter the situation and create some new opportunities for the maritime trade of non-byzantine participants, but this did not remain permanent nor become the typical situation overall. In April 1204 the Crusaders, with the support of the Venetian fleet, captured Constantinople and created the Latin Empire. The Venetians were the main benefactors of the situation and received the best quarters and ports of Constantinople after 1204, and they could navigate towards the Black Sea ports without any restrictions. Strangely enough, they were not very eager to exploit this and did not take advantage of this possibility. We have very little and only occasional evidence of Venetian ships sailing to the ports of Northern Anatolia or to the Crimea.