To counter the Genoese predominance in the southern Tyrrhenian Sea, Pisa strengthened its relationship with their traditional Spanish and French bases (Marseille, Narbonne, Barcelona, etc.) and tried to defy the Venetian rule of the Adriatic Sea. In 1180, the two cities agreed to a nonaggression treaty in the Tyrrhenian and the Adriatic, but the death of Emperor Manuel Comnenus in Constantinople changed the situation. Soon, attacks on Venetian convoys were made. Pisa signed trade and political pacts with Ancona, Pula, Zara, Split, and Brindisi; in 1195, a Pisan fleet reached Pola to defend its independence from Venice, but the Serenissima soon reconquered the rebel sea town.