The assumption by Count Guelf of the title of rector or princeps Sardiniae had, as we have seen, given equal offence to Genoa and Pisa, and when, in 1158, Frederick invited them to convey Imperial Legates to Sardinia, they did not hesitate to disobey him. If the occasion was vital enough, even the faithful Pisans knew how to separate their own policy from that of the Emperor; and, apparently, the only result of his attempt to exercise authority in Sardinia is to be found in a temporary rapprochement between the communes.

In the summer of 1160 two Pisan galleys and four saettie encountered two Saracen galleys on their way to Denia with a great Genoese merchantman which they had captured. The Pisans attacked, put the Saracens to flight and convoyed their prize to Pisa. Thereupon, ambassadors were sent from Genoa to ask that the ship should be given up to them “amore pacis et societatis.” Nor did they ask in vain. After taking counsel with the principal citizens, the consuls “navem cum toto aere pro amore et donatione Ianuensibus reddiderunt”; wherefore they gat them home again “cum amore et laetitia, et gratias ingentes referendo.” The incident is, of course, ignored by Caffaro.