<P> Forced to reduce their activities in the Black Sea, and at war with Venice, the Genoese had turned to North African trade of wheat, olive oil (valued also as an energy source) and a search for silver and gold . Europeans had a constant deficit in silver and gold, as coin only went one way: out, spent on eastern trade that was now cut off . Several European mines were exhausted, the lack of bullion leading to the development of a complex banking system to manage the risks in trade (the very first state bank, Banco di San Giorgio, was founded in 1407 at Genoa). Sailing also into the ports of Bruges (Flanders) and England, Genoese communities were then established in Portugal, who profited from their enterprise and financial expertise . </P> <P> European sailing had been primarily close to land cabotage, guided by portolan charts . These charts specified proven ocean routes guided by coastal landmarks: sailors departed from a known point, followed a compass heading, and tried to identify their location by its landmarks . For the first oceanic exploration Western Europeans used the compass, as well as progressive new advances in cartography and astronomy . Arab navigational tools like the astrolabe and quadrant were used for celestial navigation . </P> <P> In 1297, with the Portuguese part of the reconquista completed, King Dinis of Portugal took personal interest in exports and in 1317 he made an agreement with Genoese merchant sailor Manuel Pessanha (Pesagno), appointing him first admiral of the Portuguese navy, with the goal of defending the country against Muslim pirate raids . Outbreaks of bubonic plague led to severe depopulation in the second half of the 14th century: only the sea offered alternatives, with most population settling in fishing and trading coastal areas . Between 1325 and 1357 Afonso IV of Portugal encouraged maritime commerce and ordered the first explorations . The Canary Islands, already known to the Genoese, were claimed as officially discovered under patronage of the Portuguese but in 1344 Castile disputed them, expanding their rivalry into the sea . </P> <P> In 1415, Ceuta was conquered by the Portuguese aiming to control navigation of the African coast . Young prince Henry the Navigator was there and became aware of profit possibilities in the Trans - Saharan trade routes . For centuries slave and gold trade routes linking West Africa with the Mediterranean passed over the Western Sahara Desert, controlled by the Moors of North Africa . </P>

The individual most responsible for initiating portuguese voyages of exploration was