It comes as part of a set of six stamps - the fourth set of stamps in its series marking the centenary of each year of the First World War. Private Lemuel Thomas Rees' life-saving Bible was specially photographed for the stamp issue.
In 1917, Lemuel Rees was conscripted into the 6th Battalion, South Wales Borderers. During the Battle of Passchendaele, an exploding German shell landed close by, and although Rees was hit, he was saved by a small Bible that he kept in his breast pocket.
After spending four months in a field hospital, he was sent home on leave where he suffered terrible nightmares, reliving the horrors of trench warfare.
Following his return to the Western Front, Rees was wounded in a gas attack. He died from bronchial pneumonia and the effects of gas on 13th November 1918, only two days after the Armistice was signed.
The imagery on the stamps features historic memorials and artefacts that have become synonymous with the conflict, portraits of some of the participants, art showing some now famous and moving scenes, poems composed during the war and newly-commissioned artworks of poppies - the symbol of Remembrance.
Philip Parker, Royal Mail, commented: "The First World War claimed millions of lives, changed the course of history and transformed the futures of the generations that followed. We are proud to present the fourth part of our commemorative programme marking the contribution and sacrifice of those who took part."
The stamps will be on sale from 31st July from 7,000 Post Office branches across the UK.