During the mid-
Byzantine period, Sulina was a small cove, and in the 14th century, a
Genoese port inhabited by a handful of sailors, pirates and fishermen. In the 18th century, the
Ottomans built a lighthouse there in order to facilitate communication between Constantinople (Istanbul) and the Danubian Principalities, the main breadbaskets for the Ottoman capital. Thanks to the signing of the
Treaty of Adrianoupolis (Edirne) on September 2, 1829, that unfettered the Danube
grain trade, Sulina, by then under Russian control, became an important port. Great sailing boats could not sail fully loaded to
Brăila and
Galați, which were the main export centers of Wallachia and Moldavia, because of the shallow waters of the river; therefore, they had to transship at least part of their cargoes to smaller riverboats (shleps). The owners and crew of these shleps were almost always Greek. Even greater development occurred after the signing of the
Treaty of Paris (1856), which ended the Crimean War. One of the treaty's terms determined the establishment of the
European Commission of the Danube (CED), which would conduct infrastructure works on the mouth of the river in order to make it navigable for larger ships as well. The technical works allowed entrance to the Danube for a great number of "foreign", i.e. non-Greek ships, leading to a higher level of competition. River trading, however, largely remained in Greek hands. The declaration by the Ottoman administration of Sulina as a free port in 1870 also boosted its development. The
Russo-Ottoman war of 1877–1878 led to many changes as well. The city was initially put under Russian control and after the signing of the
Berlin Treaty was annexed to Romania, as was the whole
Dobruja area. According to an 1878 estimate, the town then had a total population of 800, consisting of 350
Greeks, 150
Turks, 50
Romanians, 50
Russian Old Believers and 200 others. During
World War I the city served as base for the Romanian cruiser
Elisabeta, whose actions kept the
Danube Delta under Romanian control throughout the war. In November 1916, the German submarine
UC-15 was sent on a minelaying mission off Sulina and never returned, being sunk by her own mines. This was probably caused by an encounter with the Romanian torpedo boat
Smeul, whose captain surprised a German submarine near Sulina in November 1916, the latter reportedly never returning to her base at
Varna. This could only have been
UC-15, whose systems most likely malfunctioned after being forced to submerge in the shallow waters, upon encountering the Romanian torpedo boat. In
World War II, the
Soviet M-class submarine M-59 was sunk by mines laid off Sulina by the Romanian minelayers
Amiral Murgescu,
Regele Carol I and
Dacia. ==Climate==