Louis Dubois de Nehaut (known as Le Chevalier Dubois de Nehaut) (1799-1872) Ceremony to mark the 25th anniversary of the reign of Leopold 1st at Saint-Joseph church. Brussels, July 21, 1856. Print on salted-aluminum paper, from a collodion glass negative, mounted on fine card. Photographer's dry stamp lower right. Signature and dedication in ink "Offered to Mme la Comtesse Louis Duchastel" on the mount lower right. 21 x 23 cm In July 1856, Brussels was the scene of celebrations to mark the twenty-fifth anniversary of King Leopold I's reign. Louis-Pierre-Théophile Dubois de Nehaut, who had become a member of the Société française de photographie the previous year, took what is considered one of the first systematic photographic campaigns to capture the fleeting nature of an event. Louis Humbert de Molard, who was on location at the time alongside the Belgian photographer, reports on this mission in the pages of the Bulletin de la SFP (tome 2, 1856, p. 311-314), specifying the alternating use of wet collodion "on the tumultuous masses outside" and dry collodion (Taupenot process) depending on the mobility of the subjects photographed. Some sixty negatives were produced over the three days. However, prints in circulation - if not produced - are rare, and the largest set of prints (34) known to us is held in the collections of the Royal Library of Belgium.