Fortuna Equestris is an aspect of the Roman Goddess of fate and luck Who was an especial patroness of the equestrian class or equites, sometimes called knights, as well as their horses.
The equites were originally the horse-soldiers of the Roman army, taken from the three old Roman tribes. These tribes were some of the original settlers of Rome and constituted the earliest patrician class, and were made up of the Ramnes, Latins who had a settlement on the Palatine hill, traditionally founded by Romulus; the Tities, Sabines living on the Quirinal and Viminal hills, people of King Tatius, who joined with Rome; and the Luceres on the Caelian hill, an Etruscan tribe. From these peoples were chosen both the senators and the equites; in the case of the equites one century of one-hundred horsemen from each. The state provided the horse, as well as money for its upkeep; with time the number of equites was increased, and incorporated people from other tribes. Equites were required to be of spotless character as well as of patrician or "noble" birth, and represented a sub-class of the wealthy of Rome who had special political privileges.
Fortuna had several titles relating to the classes of Roman society. She was known as Fortuna Patricia, Fortune of the patrician or noble class; Fortuna Plebis, Fortune of the plebeians, the common people who were originally those descended from the conquered Latin tribes and who did not have the rights and privileges of the patricians; and Fortuna Equestris of the equites. These epithets indicate just how deeply divided ancient Roman society was by class, as they needed three separate and distinct varieties of Fortuna so each class could have its own.
Fortuna Equestris had a temple at Antium, the modern Anzio, which was once the capital of the Volsci of Latium, a tribe who spoke a language closely akin to Umbrian, and who were often enemies of Rome; She may originally have been a Deity specific to that area. She also had a temple in Rome itself, built by Flaccus, a consul (roughly a "president" of Rome under the Republic), who vowed to build it during a battle with the Celts of Iberia (Spain). He made it out of the battle alive, and in 173 BCE dedicated Her temple in the Circus Flaminius (actually a square rather than a horse-track—the temple to Juno Regina was located there as well), near to the Theatre of Pompey. He also appropriated some fancy marble tiles for Fortuna's temple from the splendid temple of Juno Lacinia near Croton, but the Senate made him put them back.
The festival of Fortuna Equestris was August 13th, the date of the dedication of Her temple in Rome.
She may be equated with Fortuna Manens, "Constant Fortune"