 Complete the following phrase:  Pisa, at that time overlooking the sea at the mouth of the Arno, reached the pinnacle of its glory between the 12th and 13th centuries, when its ships controlled the Western Mediterranean. Rivalry between Pisa and Genoa grew worse in the 12th century and resulted in the naval Battle of Meloria 1284, which marked the beginning of Pisan decline; Pisa renounced all claim to Corsica and ceded part of Sardinia to Genoa in 1299. Moreover, the 