The Macedonian phalanx (and the earlier Hoplite phalanx) was a mass military formation in the shape of a rectangle. A variant of the defensive shield wall, the phalanx was also a fearsome offensive tactic to be reckoned with in the ancient world from around the 3rd-century B.C., to the rise of Rome around the 2nd-century B.C.
Basically, a large group of hoplites line up in columns and rows. Armed with small shields and insanely long spears, the phalanx would march into battle, slaughtering any melee combatant foolish enough to attempt an approach.
A gallery of awesome-looking depictions of the phalanx formation follow below:
Image from P. Connolly, The Greek armies, 1978

The Sarissa was the spear of choice for phalanx assaults. Measuring around 5.5 metres (18 feet) long, the sarissas of the first several rows of men would jut out through the front line, creating a wall of piercing death.
Behold the size comparison to puny, soft-fleshed human victims below:
Sarissa images from University of Canterbury
And if you don’t think all that sounds scary, imagine yourself as a tribal warrior, armed with your puny broadsword (a mere 1.8 metres or 6 feet long) and wearing only war paint, magical wards and your own courage for armour, charging face first into a dozen spearpoints with a pathetic battle cry.
The outcome, in DotA speek: “MEEEEEEEEGA KILL!!!”
Compare to the later Roman Testudo (tortoise) formation where interlocked shields protect the top and every side.
Less scary looking, and more defense oriented for such uses as getting close to the enemy walls during a siege. (I recall the Uruk Hai using this formation in order to get a battering ram to the side gate during the siege of Helms Deep in Lord of the Rings: The Two Towers film.)
Back to the phalanx: This marching wall of doom had several weaknesses, however. It was bulky and unagile, for one, unsuited for use on uneven terrain.
It was slow moving, allowing ranged attackers to gradually wither down the soldiers from afar. Siege weapons such as catapults and ballistae, normally too inaccurate for use against infantry, would have devastated the easy target of the large, nearly-immobile mass of men.
The sides and back of the formation were especially vulnerable – turning and wheeling would have been like trying to park a lorry. Pike walls are a counter to cavalry charges, but fast moving cavalry could bypass the front of the phalanx and strike the flanks.
Thus, the phalanx often fared better when supported by light infantry and cavalry to counter the opponent’s flexibility.
So as time passed and Warfare evolved, the phalanx eventually became outdated as more adaptable tactics were adopted. But the tactic continued on in different forms, such as in combination with musketeers as in the 16th- and 17th-century Spanish Tercio.
And of course, the phalanx remains a popular battle formation in strategy games featuring the glorious ages of ancient warfare. (Although sometimes inaccurately depicted.)
Shields up! Heads down! Spears forward… Advance!
And here’s some shots of the Spartan hoplite phalanx as portrayed in the cinematic battle-fest film, 300 (no larger size available even if you click them):
The film portrayal clearly shows the tactical advantage that well-drilled professional soldiers with thick, strong spears and heavy bronze shields have against inexperienced conscripts (called ‘an army of slaves’ by the Spartans) armed with light weapons and wicker shields.
Fan spliced music video of battles in 300 at Youtube here.
The barechested hoplites of the film are not exactly accurate, however (though it makes for macho comic book and movie posturing). The real hoplites were heavily armoured, more like this:
An earlier film about the Battle of Thermopylae, the 1962 release The 300 Spartans has its history more accurate and much less sensationalized.

And finally… An editorial cartoon playing on the War on Terror (Iraq campaign) from Cox and Forkum:















