From being involved in piracy against Byzantine merchants, to being home to the first men to scale the mighty walls of Jerusalem in 1099, the Medieval Pisan “Res Publica” was a maritime republic that blossomed in the Early Middle Ages and dominated the Western and Eastern Mediterranean trade routes, until its decline in the late 13th century when Guelph Genoa’s power rose.
After the naval incursions of the Saracens into the Western Mediterranean in the 9th century AD, some Italian urban communities (Amalfi, Naples, Gaeta etc.) organized themselves into efficient naval powers to combat the Muslim incursions. The city of Pisa, previously a Roman port and a seat of a Lombard Gastald, was one of the first to organize itself in such a way. Great “Patrician” (in a clear reference to ancient Rome) families (such as Gualandi, Orlandi, Della Gherardesca, Caetani, Lamberti, etc.) started to emerge in the city, arming entire fleets of war galleys (Dromones) and trade ships, and building their fortified palaces on the Arno. The city government at this time consisted of a group of elders (who met in what is today Palazzo della Carovana in piazza dei Cavalieri) who elected consuls (most of the consuls were from the aristocracy) from their ranks, the city Archbishop and aristocrat Consorterie (aristocratic Corporations/factions).
Pisan fleets started raiding Muslim naval bases on Mediterranean islands (like the Balearic Islands) and North Africa, while also attacking and sacking other Christian naval powers like Amalfi in southern Italy. Pisan merchants and sailors were known to highly value holy relics (like soil from inside Jerusalem) establishing colonies and trading posts in Constantinople, Acre, Jaffa, Thessalonica, Gaeta and the islands of Elba and Giglio. Fortified castles (Castra) and watch towers were often built in these locations in order to watch over naval trade routes and act as bases for travelling vessels while sailors were mainly based in the Porto Pisano, a fortified harbor near modern day Livorno in the Sinus Pisanus (Gulf of Pisa), already in use in Roman times. Pisan merchants and ship captains bearing a completely red flag (the medieval flag of Pisa) helped the Christians during the First Crusade and especially during the Siege of Jerusalem in 1099 by providing supplies and timber for the Crusader army and siege engines, thus demonstrating an enormous influence also over the Eastern Mediterranean.
During its height, Pisa financed the building of a great cathedral with a bell tower (which will become its now famous Leaning Tower) outside the city walls, flanked by a monumental aristocratic cemetery, recruiting stone masons, architects and engineers from all over Europe and the Mediterranean, as further proof of the city’s power and wealth. Being fiercely Ghibelline, the city of Pisa and its main families provided war fleets to Holy Roman Emperors such as Frederick II Hohenstaufen and also supplied the imperial court with intellectuals like Fibonacci, architects like Nicola Pisano and naval commanders like Orlandi consuls.
The decline of the powerful Pisan fleet came however with the rise of the naval power of Guelph Genoa (almost always allied with the Roman pontiff), a bustling city located in Liguria which decisively defeated the Pisans in a massive naval battle at the Tower of Meloria (near the Porto Pisano) in 1284, after having raided Pisan territory and strangled its trade routes throughout the Mare Nostrum, which were its main source of wealth, ultimately conquering the Pisan Territories in Corsica and Sardinia in 1299. The city continued its steady decline throughout the subsequent Medici dominance on the Renaissance, during which time many wealthy and mercantile families emigrated from the city to escape Florentine control.