This was a battle fought in 1571 I believe, between the Ottoman Empire and a coalition of the Spanish Empire, Venice, the Holy See, and the Knights of Malta. It was a hard fought naval battle that occurred at the end of the campaigning season when no one really thought there would be a fight.
It last about 4 hours and the Turkish fleet was destroyed and about 40,000 Turks and slaves drowned or killed.
The battle is very interesting to study. At one point the two flag ships were crushed up against each other and a battle raged on both their decks, men being fed into the maelstrom from other ships on gangplanks and the like.
It was crazy brutal.
Don Juan, the leader of the Christian armada (not to be mistaken with the lover of the same name) used a two handed sword in the battle, to cleave and punch his way through the Turkish ranks. The leader of the Turks fought to the bitter end, holding his flagship against the Spanish until he was shot in the head.