Don John, victor at the Battle of Lepanto, 1571

Don John was the bastard son of Charles V, the Holy Roman Emperor.
Born in Germany but raised in Spain, Don John's (half) brother was the Spanish king, Philip II. As per his father's wishes, Philip officially recognized his brother and gave him a title and income. Philip, 20 years older than the young Don John, wished that his brother would enter the Church, but Don John desired a military career. He fought against Barbary pirates at the age of 21. When he was 24, Philip put him in charge of the navy of the Holy League, an alliance of Catholic states.
On October 7, 1571, off the coast of Greece, the Holy League navy was met in battle with the Ottoman fleet. This was the last major battle in history where both sides used only galley ships with oars. This was the Battle of Lepanto.

The battle resulted in a massive Turkish defeat - Turkish casualties were around 30,000, as well as over 200 ships. The Holy League suffered 9,000 casualties, but freed twice this number in Christian prisoners. Their navy captured about 140 seaworthy vessels.
While the Ottomans later rallied and rebuilt their navy, they had lost control of the seas.

Don John, a true defender of the West.