Former Royal Army Service Corps member Edd Mortimer, 85, penned a message yesterday on a huge art installation that has been placed beside the River Thames in London.
The 2.4m-high artwork, which spells out "thank you", is to honour those who fought in and lived through World War I.
It was put up by The Royal British Legion, a charity that helps British armed forces veterans and their families, to give thanks to "all who served, sacrificed and changed our world", reported the BBC.
This year marks the 100th anniversary of the end of the war.
The artwork features a design by artist Sarah Arnett that comprises various images of the war, such as the "Munitionettes" - British women who worked in weapons factories - and Indian infantrymen who served on the Western Front.
It also includes blank spaces for the public to add their own messages.