The pilos was a typical conical hat in Ancient Greece among travelers, workmen and sailors, though sometimes a low, broad-rimmed version was also preferred, known as petasos. It could be made of felt or leather. Pilos caps often identify the mythical twins, or Dioscuri, Castor and Pollux, as represented in sculptures, bas-reliefs and on ancient ceramics. Their caps were supposedly the remnants of the egg from which they hatched. The pilos appears on votive figurines of boys at the sanctuary of the Cabeiri at Thebes, the Cabeirion. In warfare, the pilos type helmet was often worn by the peltastlight infantry, in conjunction with the exomis, but it was also worn by the heavy infantry. The pilos helmet was made of bronze in the same shape as the pilos which was presumably sometimes worn under the helmet for comfort, giving rise to the helmet's conical shape. Some historians theorize that the pilos helmet had widespread adoption in some greek cities such as Sparta, however, there is no primary historical source or any archeological evidence that would suggest that Sparta or any other greek state would have used the helmet in a standardized fashion for their armies. What led historians to believe that the helmet was widespread in places such as Sparta was, amongst other reasons, the supposed advancement of battlefield tactics that required that infantry have full vision and mobility. However, many other types of greek helmet offered similar designs to the pilos when it came to visibility, such as the konos or the chalcidian helmets, and the idea that Sparta widely adopted the pilos helmet, or any type of helmet in a standard fashion, is based purely on speculation, since any surviving records of classical historians such as Herodotus or Xenophon never gave such an account of a precise type of widespread equipment or helmet the greeks wore at any point in time.
Illyria
The plis, an Albanian felt cap, originated from a similar felt cap worn by the Illyrians.
Rome
In Ancient Rome, a slave was freed in a ceremony in which a praetor touched the slave with a rod called a vindicta and pronounced him to be free. The slave's head was shaved and a pileus was placed upon it. Both the vindicta and the cap were considered symbols of Libertas, the goddess representing liberty. This was a form of extra-legal manumission considered less legally sound than manumission in a court of law. One 19th century dictionary of classical antiquity states that, "Among the Romans the cap of felt was the emblem of liberty. When a slave obtained his freedom he had his head shaved, and wore instead of his hair an undyed pileus." Hence the phrase servos ad pileum vocare is a summons to liberty, by which slaves were frequently called upon to take up arms with a promise of liberty. The figure of Liberty on some of the coins of Antoninus Pius, struck A.D. 145, holds this cap in the right hand. In the period of the Tetrarchy and subsequently a distinctive type of round, brimless hat known as the Pannonian cap was worn as part of a Roman soldier's costume, though it also seems to have been worn by non-military bureaucrats. It was flat topped and resembled the more recent 'pillbox hat'.
