Complex sentence: On 13 February, a Venetian-Aragonese fleet met the Genoese near Constantinople in the indecisive Battle of Bosphorus and inflicted heavy losses on both sides, but in the end Venice had to abandon the Bosphorus and the Aragonese fleet was hardest hit.
Split into simpler sentences: On 13 February, a Venetian-Aragonese fleet met the Genoese near Constantinople in the Bosphorus. The battle was indecisive and inflicted heavy losses on both sides, but in the end Venice had to abandon the Bosphorus and the Aragonese fleet was hardest hit.