It’s a flail, NOT A MACE!
You will inevitably hear some ignoramus try to call a flail a mace, but the mace is actually an entirely different weapon from the flail. The mace has a head fixed on a handle. The flail has a handle with chains connecting to the head or heads.
Construction of a flail
Most flails have a hard wooden handle that may vary in length but are generally around a foot and a half long, connected to one or more chains of about the same length (the number of chains depending on whether or not it is a single headed, double headed, or triple headed flail) to the head or heads. The heads are heavy balls of metal that are, for the most part, spiked. This weapon is perhaps one of the least costly and least time consuming to make in all of the middle ages, but when used correctly, one of the most deadly.
There are, however, many variations as far as what the flail can be made of. There are flails that have a metallic handle; be it steal or iron. They also may have flanged balls as the heads instead of the spiked ones that were more common.
History of the flail
There is not much known about when and where the flails where actually first used (although many different opinions are out there…) What is known is that the flail was a variation of an old farming tool. The agricultural flail was used to thrash wheat. This led to the weapon being a favorite for peasants in militant groups to use, as they already knew how to handle it.
Now, this leads us to an interesting thought.
Before the War of the Roses, and the 100-Years War between England and France, there was the “Code of Chivalry” that stated, in an overview, that only knights can fight knights, along with other rules and codes of war. So, for the majority of the civilized medieval world (not pre-Middle Ages) “Code of Chivalry” would mean that a farm working peasant would not be conscripted to fight against knights in armor, as peasants could never wear it. The flail was designed to crush armor, as we will discuss later. However, chivalry died when the English began using archers against their French foes. Thus, the code was broken, and England began to use any and everything they had to defeat the French, including peasant armies to fight against the knights.
Thus, as a personal opinion, the flail was first widely used in the Middle Ages during the 100-Years War by the English to defeat the French, along with, of course, the longbow (another non-chivalrous weapon).
Use of the flail
As stated, the flail was designed to crush armor. Think about it, if you were to face a knight in full plate armor with a regular sword, chances are you are going to be a while; even if you are the better swordsman by far, to kill him. Full suits of armor do not have many places where a sword is going to be an effective killing tool against. This played into the “Code of Chivalry”, as part of the code was that one chivalrous knight should try not to kill his opposing chivalrous knight, just better him.
(Keep in mind that the “Code of Chivalry” was a hypocritical oath that definitely did not affect many areas and was very short lived!)
Either way, there was a need for weapons that would actually kill a man in full armor. Thus the bashing and crushing weapons made their way back onto the battle field. Simplistic weapons such as the hammer and clubs were modified. All had one agenda, to dent the armor and incapacitate the man inside.
To use a flail, especially the double and triple headed ones, took skill. Imagine, if you can, that you are swinging not one, but two or three chains with a weighted ball on the end of each chain, and directing them to a specific, small, moving target, all the while making sure not to leave yourself open to a counter attack. This is to say that the farmers who used the agricultural variation of the weapon knew how to swing the weapon from using it in fields, but the intricacies had to be learned, hopefully not the hard way.
The flail not a defensive weapon
The flail was an offensive power to be reckoned with. However, it was a defensive liability. A man using the flail relied on his shield for all defensive purposes. With most other weapons, mainly the sword, the weapon itself could be used defensively as well as offensively. With the sword, one could block and parry an opponents attack with the blade. With the flail, there was no way to do so with the weapon. This meant that the flail user had to be proficient with his shield to block an opponents attack. Also with the sword, one could use a sword and shield combination of defense, making both sides of the body defended. With the flail, the user would have to bring the shield arm from one side of the body across to the other side. (So if I had the flail in my right hand and shield in left, to block an attack on my right side, I would have to bring my left arm across my body to the right side to block the attack before it hit me).