Passage: The first part of the Renaissance saw almost constant warfare on land and sea as the city-states vied for preeminence.  On land, these wars were primarily fought by armies of mercenaries known as condottieri, bands of soldiers drawn from around Europe, but especially Germany and Switzerland, led largely by Italian captains.  The mercenaries were not willing to risk their lives unduly, and war became one largely of sieges and maneuvering, occasioning few pitched battles. It was also in the interest of mercenaries on both sides to prolong any conflict, to continue their employment.  Mercenaries were also a constant threat to their employers; if not paid, they often turned on their patron.  If it became obvious that a state was entirely dependent on mercenaries, the temptation was great for the mercenaries to take over the running of it themselves—this occurred on a number of occasions.At sea, Italian city-states sent many fleets out to do battle. The main contenders were Pisa, Genoa, and Venice, but after a long conflict the Genoese succeeded in reducing Pisa.  Venice proved to be a more powerful adversary, and with the decline of Genoese power during the 15th century Venice became pre-eminent on the seas. In response to threats from the landward side, from the early 15th century Venice developed an increased interest in controlling the terrafirma as the Venetian Renaissance opened.

Question: Who were competing for dominance when the Renaissance began?
city-states