The Glorious Twenty-Fifth of May (sometimes also referred to as Wear the Lilac Day) is a fan observance celebrating the life and work of English writer Sir Terry Pratchett, who is best known for his comic fantasy book series Discworld.
Pratchett’s books frequently parody, or take inspiration from, J. R. R. Tolkien, Robert E. Howard, H. P. Lovecraft and William Shakespeare, as well as mythology, folklore and fairy tales, often using them for satirical parallels with current cultural, political and scientific issues.
In the series’ 29th book, Night Watch, certain members of the Ankh-Morpork City Watch, and a few others around the city, wore a sprig of lilac on the 25th of May. It was the day they remembered those who fought and fell for hardboiled eggs, truth, justice and reasonably priced love. It was a rememberance of those who died – and, in Reg Shoe’s case, rose and kept fighting – in the Glorious Revolution of Treacle Mine Road.
Fans across the world commemorate the Glorious Twenty-Fifth of May by wearing lilac and supporting research into Alzheimer’s disease. Pratchett was diagnosed with the disease in 2007.