The story of the Angel of Mons is one of the enduring myths of WW1 and it has been analysed countless times so I really don't need to rehearse the development of this story here, the Wiki page is a very good introduction. Suffice it to say it is widely thought to be an example of fiction into fact: a fictitious story by Arthur Machen about an apparition of bowmen from the Battle of Agincourt appearing at Mons and offering aid to the British troops, seems to have taken on a life of it own, morphed and changed very quickly until it was being very widely reported as true. I can remember as a child reading books about ghosts and strange happenings and reading this story reported even then as if the reports had actually come from the battlefield. A friend of mine tells me she read the story reported in this way in a magazine just a few months ago.
One of the key points in the translation of the story from fiction into.. well, 'metafiction' was its being taken up by local church groups and published in church magazines and in pamphlets. So I was delighted to find this. Admittedly undated, but I think fairly contemporary this ephemeral little tracts is probably a scarce item now. A quick glance through the text will show just how 'ephemeral' the story had become even by this point with reports from relatives of friends of nurses... etc. etc.