The Duke, who began his Naval career in 1939, fittingly marks the end of his public programme by attending a parade with the Royal Marines at Buckingham Palace.
As announced in May 2017, The Duke will no longer undertake his own programme of public engagements, although he may choose to attend certain events, alongside The Queen, from time to time.
His Royal Highness's association with the Royal Marines dates back 64 years to 2nd June 1953 upon appointment as Captain General in succession to the late King George VI.
He has also been has been Honorary President of the Royal Navy and Royal Marines Association and Club since 1948. The Royal Marines are the amphibious light infantry force that forms part of the Naval Service.
Today's parade marked the finale of the 1664 Global Challenge, which has been raising funds and awareness for The Royal Navy Marines charity – and symbolises the significance of 1664 as the year in which the Corps was founded. This year, the challenge saw Royal Marines from around the country running 16.64 miles each day for 100 days, totaling a distance of 1664 miles.
The Duke met representatives from the runners' contingent, including two Royal Marines who have completed the entire 1664 miles.
His Royal Highness also spoke to veterans and cadets before returning to the dais to receive the 1664 Global Challenge baton.
The Parade concluded with a march past, a Royal Salute and three cheers for the Captain General.