Frederick of Hesse-Darmstadt
Frederick was born in Darmstadt, Germany, the 12th child of Louis V, Landgrave of Hesse-Darmstadt. Born into a Lutheran family, he converted to Catholicism at the age of 20 and entered the Order of St. John of Jerusalem.
He served as a soldier during a number of conflicts and became an admiral in the navy of the Kingdom of Spain. In 1647 he became Grand Prior of the Order of St. John in Germany and travelled throughout Italy, Spain and Germany.