Equerry is a bygone title, a relic of the Great Crusade era of early Imperial history in the late 30th and early 31st Millennia. Space Marines who were selected for the honour by a superior officer were known as Equerries, and served as a trusted comrade and a confidant to the senior officers of their Space Marine Legion. The highest honour was reserved for those Astartes selected to serve as Equerries to their Primarchs, the genetic forebears and masters of the Legiones Astartes. At the time, it was also customary for senior military officers from all corps of the Imperial Army to perform in a similar role by selecting a more junior officer as an aide-de-camp. By the late 41st Millennium, the practice had fallen out of favor, but some Astartes Chapters keep the tradition alive by assignin