The Arms, Armor, and Iconography of Early Greek Hoplite Warfare
The Greek Hoplite (c. 700-500 BC). Although elements of the bronze panoply associated with the classical hoplite began to appear in the late eighth century, what set the hoplite apart from his predecessors was above all his distinctive heavy wooden shield with a double handle, which is first attested circa 700 BC. This date may therefore be regarded as the beginning of the hoplite era. A great deal of the debate about the origins of the classical phalanx centers on what the adoption of this type of shield might imply about the nature of hoplite fighting and battle formations.
Viggiano, G.F. & Wees, H.V. (2013). The arms, armor, and iconography of early Greek Hoplite warfare. In Kagan, D. & Viggiano, G.F. (Eds.). Men of bronze: Hoplite warfare in ancient Greece (pp. 57-73). Princeton, NJ: Princeton University Press.