Rememberance Day at The Cenotaph. Remembrance Day (also known as Poppy Day owing to the tradition of wearing a remembrance poppy) is a memorial day observed in Commonwealth member states since the end of the First World War to honour armed forces members who have died in the line of duty. Following a tradition inaugurated by King George V in 1919, the day is also marked by war remembrances in many non-Commonwealth countries.