The eastern bay of the Mediterranean was, for much of the age of fighting sail, a secure ‘Ottoman lake’, through being surrounded by mainland coastal territory ruled in its entirety from Istanbul. In terms of being a protected lake, this was a description that applied with even greater force to the Black Sea where, for many years, the role of the Ottoman navy was simply to ensure that the various suzerain states conformed to the wishes of the Sublime Porte, and where piracy had also been more or less eradicated. It was Cossack raids emanating from ungoverned areas to the north and beginning some time during the mid-sixteenth century which began to undermine this situation, a point made by Guillaume Le Vasseur de Beuplan (1600–73), a French army engineer and cartographer who, in 1639 travelled the Dnieper by boat. In his Description d'Ukranie, de Beuplan provides clear evidence of Cossack activity and the uncertainty caused by their raiding activities among those whose lives were intertwined in some way with the Black Sea and its littoral. According to de Beuplan, the Cossacks used shallow-draughted rowing boats that rose just a little over a metre above the water and were usually equipped with a small cannon. These boats, often manned by as many as seventy and assembled in tightly grouped fleets of up to 300, were highly manoeuvrable, having rudders both at the bow and stern. When such a fleet of Cossack boats attacked large merchant galleys at sea, de Beuplan wrote: