This card could be based on the Macedonian Phalanx formation, used in their military campaigns by Alexander the Great. The phalanx formation was also used by the Greeks. The formation is a bunch of soldiers who line up side by side. One soldier protects the soldier on the left. This might refer to the fact that Phalanx is the "shield," thus when it is equipped, it "lines up" with the monster it is equipped to on the field.