A hypaspist (Greek: Ὑπασπιστής ”shield bearer” or “shield covered”) is a squire, man at arms, or “shield carrier”. In set piece battles the Macedonian Hypaspists were positioned on the flanks of the phalangite’s phalanx, with the light infantry and cavalry, respectively, covering their flanks. Their job was guard the flanks of the large and unwieldy pike phalanx.
http://en.wikipedia.org/wiki/Hypaspists

hypaspist (Greek: Ὑπασπιστής ”shield bearer” or “shield covered”) is a squire, man at arms, or “shield carrier”. In set piece battles the Macedonian Hypaspists were positioned on the flanks of the phalangite’s phalanx, with the light infantry and cavalry, respectively, covering their flanks. Their job was guard the flanks of the large and unwieldy pike phalanx.

http://en.wikipedia.org/wiki/Hypaspists