rred the resentment of cities like Lucca, Massa, Volterra and Florence, who saw their aim to expand towards the sea thwarted. The clash with Lucca also concerned the possession of the castle of Montignoso and mainly the control of the Via Francigena, the main trade route between Rome and France. Last but not least, such a sudden and large increase of power by Pisa could only lead to another war with Genoa.
Genoa had acquired a largely dominant position in the markets of Southern France. The war began presumably in 1165 on the Rhône, when an attack on a convoy, directed to some Pisan trade centres on the river, by the Genoese and their ally, the count of Toulouse failed. Pisa on the other hand was allied to Provence. The war continued until 1175 without significant victories. Another point of attrition was Sicily, where both the cities had privileges granted by Henry VI. In 1192, Pisa managed to conquer Messina. This episode was followed by a series of battles culminating in the Genoese conquest of Syracuse in 1204. Later, the trading posts in Sicily were lost when the new Pope Innocent III, though removing the excommunication cast over Pisa by his predecessor Celestine III, allied himself with the Guelph League of Tuscany, led by Florence. Soon he stipulated a pact with Genoa too, further weakening the Pisan presence in Southern Italy.
To counter the Genoese predominance in the southern Tyrrhenian Sea, Pisa strengthened its relationship with their Spanish and French traditional bases (Marseille, Narbonne, Barcelona, etc.) and tried to defy the Venetian rule of the Adriatic Sea. In 1180 the two cities agreed to a non-aggression treaty in the Tyrrhenian and the Adriatic, but the death of Emperor Manuel Comnenus in Constantinople changed the situation. Soon there were attacks on Venetian convoys. 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,
