A Portuguese historian believes he has solved the age-old mystery surrounding the nationality of Christopher Columbus. According to Manuel Rosa, a lecturer at Duke University, North Carolina, the explorer was in fact the son of Polish King Władysław III. It has always been thought that King Władysław III fell in battle against the forces of the Ottoman Empire at the Battle of Varna in 1444. According to Mr Rosa, however, the king managed to survive the battle unscathed and fled to the Portuguese island of Madeira where he lived out the rest of his life as a hermit and married...