The Battle of Lepanto is the mother lode of historical naval turning points. It broke the Ottoman Empire’s domination of the eastern Mediterranean and marked a turning of the tide in the long-simmering conflict between the European powers (particularly the Habsburgs) and the Ottomans. It gave European Christians the confidence that they could stand up to the feared Ottomans and actually come away with a major victory.
Well, kind of. I mean, it did those things, more or less, but not suddenly and not even very apparently in the years immediately following the battle. Lepanto had far-reaching impacts, but most of them took a while to really shake out. And one of its most far-reaching impacts actually had very little to do with the European-Ottoman conflict and everything with the way naval warfare would be conducted from then on.