In the game Quatre Bras as well as Waterloo, an attempt is made to simulate the use of the three arms of Napoleonic warfare: infantry, cavalry and artillery. When confronted by cavalry, an infantry unit will form a SQUARE. When cavalry is not near, an infantry unit will stay in or revert to LINE formation. Cavalry is vulnerable to the bristling bayonets of an infantry square while an infantry unit in line can be run down by cavalry. A square, on the other hand, is an easy and compressed target for artillery and infantry in line. And artillery is easy prey for infantry in line and cavalry. The snap below shows an Allied unit being forced into square by cavalry then ready to be raked by infantry and artillery fire.