The Schiltron formation is one of the Greek phalanx-like arrangement of soldiers wearing skewers. This formation was used by the Scottish commanders during the Scottish War of Independence to compensate for the inferiority of their own infantry against the better trained and equipped English soldiers and cavalry.
The principle, like the phalanx, consists of a dense wall of spears, so that opposing soldiers can not reach their own soldiers within reach of their weapons, but are always kept at a distance and can be attacked by the spies themselves.
Unlike the phalanx, the Schiltron formation was not a line but a quadrangle. This should exclude enemy flank attacks and rear attacks.
The Schiltron formation could, however, never prevail militarily outside Scotland. The main aspects of his failure were, on the one hand, the high degree of discipline that was necessary to not break up such a formation in combat, on the other hand, the backs of the soldiers were not protected against attacks by archers, so that gave these easy goals.