En chamade (French: "to sound a parley") refers to powerfully-voiced reed stops in a pipe organ that have been mounted horizontally, rather than vertically, in the front of the organ case, projecting out into the church or concert hall. They produce a commanding, loud trumpet-like tone, used for fanfares and solos.
Any stop mounted en chamade will be much louder than a stop elsewhere in the organ, even though in church organs the stops stand on the same windpressure. In theatre and concert organs, en chamade stops often stand on higher windpressure than the other stops, to sound even more powerful and commanding.
First seen in Iberian and Mexican organs of the early eighteenth century, it came in many forms to form choruses in divided registers: the Trompeta de Batalla (8'), Bajoncillo(4'), Bajo (16'), Violeta (2'), Trompeta Magna (16'), the Claríns (either 8' or 4', the smaller ones in conjunction with the trompetas). Unlike the modern chamade trumpet, these all stood on pressures of 55 mm, which is about 2 inches, compared to anywhere from 10 inches to 50 inches. Often confused with these are the Trompeta Reales, or Trombeta Reales, which were always located inside of the case.* Another example, first referred to as a trompette 'en chamade' is located in an organ built in Provence in 1772. The term was popularized by Aristide Cavaillé-Coll in his organs of the nineteenth century.
Chamade was a trumpet call designed to be heard across the battlefield in the enemy camp, just before a charge.