In the following years, Pisa was one of the staunchest supporters of the Ghibelline party. This was much appreciated by Frederick I. He issued in 1162 and 1165 two important documents, with these grants: Apart from the jurisdiction over the Pisan countryside, the Pisans were granted freedom of trade in the whole empire, the coast from Civitavecchia to Portovenere, a half of Palermo, Messina, Salerno and Naples, the whole of Gaeta, Mazara, and Trapani, and a street with houses for its merchants in every city of the Kingdom of Sicily. Some of these grants were later confirmed by Henry VI, Otto IV, and Frederick II. They marked the apex of Pisa's power, but also spurred the resentment of cities such as Lucca, Massa, Volterra, and Florence, thwarting their aim to expand towards the sea. The clash with Lucca also concerned the possession of the castle of Montignoso and mainly the control of the , 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.