The window, which is expected to bring €7000, is the work of the Belgian artist Raphael Évaldre (1862-1938). Even though he is regarded as one of the most important maître-verriers of the Art Nouveau period, little is known about Évaldre.
He trained under Louis Comfort Tiffany and worked with the leading architects of his day, including Paul Saintenoy and Victor Horta.
The window on offer was part of a villa near Spa-Francorchamps, south-east of Liège. When the house was demolished in the 1970s, the window was saved and has been in possession of a Frankfurt collector ever since.
The central panel of the signed window depicts three cherubs, one writing in a book, another with an olive branch and one as a resting warrior.
Above them are military trophies, a garlanded helmet, a quiver and a wreath of laurel leaves. According to tradition, the three cherubs are idealised portrayals of the three men who commissioned Évaldre with the decoration of their villa.