Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
Commander (order)
"Knight Commander" or "Dame Commander" is the second most senior grade of seven British orders of chivalry, three of which are dormant (and one of them continues as a German house order). The rank entails admission into knighthood, allowing the recipient to use the title 'Sir' (male) or 'Dame' (female) before his or her name. In the Commonwealth Realms orders and decorations, Knight Commander and Dame Commander rank before Knights Bachelor but after the Order of the Companions of Honour, although Companions of Honour obtain no knighthood or other status.