The Roman Catholic Diocese of Metz is a Diocese of the Latin Rite of the Roman Catholic church in France. In the Middle Ages it was in effect an independent state (prince-bishopric), part of the Holy Roman Empire, ruled by the prince-bishop who had the ex officio title of count. It was annexed to France by King Henry II in 1552; this was recognized by the Holy Roman Empire in the Peace of Westphalia of 1648. It then was part of the province of the Three Bishoprics.