The usage of Capital Letters as Shield devices
Most scholars generally agree that the use of the first capital letter from the name of the City State as an emblem on their hoplites shields, started from the fourth century BC.
The main literary source is the «HELLENIKA» of Xenophon where in the fourth chapter of his fourth book mentions in paragraphs from 9 to 12 that the Sikyonians had the capital Greek letter «SIGMA» on their shields and when the Spartans horsemen attacked the Argives after they collected the abandoned shields of some Sikyonian fugitives. The Argives were not worried because they thought they were facing Sikyonians. On this text piece many people support the hypothesis that the Laconic shield device of the time was the «LAMBDA» Laconic shield device of the time was the «LAMBDA» and that its very appearance on the battlefield caused terror.
A second literary source is the «Dictionary» of Photius in which the author quotes the Athenian poet Eupolis who writes that the Messenians use the capital letter «M» on their shields and he is commenting the same for the Spartans when he describes the Letter «Lambda». There is ground for doubting this as all evidences is just a logical guess basse on a medieval source. The «LAMBDA» appears on Hellenistic Spartan coins of king Kleomenes III and again not on its own thus creating further doubt on its usage as a shield device.
Pottery art of the ancient period, however gives indication that the Athenians may have started adopting the capital letter «A» as a shield device quite earlier. The attic vases show the letter «A» arround 421 BC but most images however depict hoplite races and speculated that the shields carried by the hoplites depicted were issued by the State for the needs of the sport and not for war.
One image of a hoplite race from the Archaeological Museum of Rhodes allows us to date the usage the capital letters as shield emblems before the middle of the fifth century, however, a black figure cup at the Museum of Cycladic Art in Athens demonstrates the use of this emblem in warfare in the mid sixth century BC. The dating of the capital letter «A» usage probably need to be revised.