A shield is a simple board of any material resistant enough to receive a blow and let its wearer survive. That simple. There are uncountable kinds of shields all over the world and each culture has its own distinctive form(s). My personal favourite: the germanic round shield, around 80 centimeters in diameter and with an umbo (round metal piece) and a nice painting on the front part. But this defensive item has a wider function than many other people think of.
Let us start first with a little review on shields in the Middle Ages, since this is my area of expertise. Most of the shields I will describe will have similar use in other cultures.
As stated before, shields are an integral part of many warriors in the past. They used to have a different size depending of the need. Romans were known for carrying huge and long defense, oftentimes covering the whole body. Those are known as towers-shields, used to create lines of defense. This way, the infantry could hold attacks on open fields easily. Part of the normal weaponry of the legionary allowed the roman empire to expand its territory, since the using of that protection required a lot of group training and discipline.
Still, the biggest weakness was its use in close quarters and with no space. Because of its size it did not permit the common soldier to move freely, and not any weapon was usable behind that little wall. Usually it was accompanied by a short to long lance-like weapon and a short sword to be able to grab the weapon with the other hand. Soon enough, the barbaric tribes of the north and the east destroyed the highly static infantry by making ambushes. The battle at Teutoburg was only one of the many battles that showed the weaknesses of the otherwise excellent roman military education.
The germanic people themselves tried not to use shields, but when acting as a unified force (which was more often than imagined) they were able to seal off vast expanses of the battlefield making a similar wall to their roman counterparts. Since the shield was smaller, the mobility increased incredibly. Now the soldiers could duck under the shield for a barrage of arrows and then move on to a charge. Still, the shield bas bulky and heavy on the arm of the fighter. By my own experience I can state that it required a good mastery to be able to fight effectively with it. Specially in tight spots of a fray, when single combat became the main way to reach an enemy, the round shield, made of leather and wood, was discarded. Part of this became later part of the myth of the beserkr, a warrior that eschewed the protection for an all frontal assault and, thus, became invincible.
Later on, as the crusades drew neared, the european warriors started to make the shield smaller and the armour pieces tougher. I will talk later about the armor, but for the sake of this article, I will just say that the chain mail started to cover the body more and more, making the triangular shield a perfect option for quick protection against immediate physical attacks and rains of arrows. Still a bit cumbersome, the shield did only protect less than half a body, but it became easier to carry (only with the hand instead of the full arm) and thus easier to leave behind in case of tight situation.
Finally, for the XVth century, the shields were almost non-existent. Many people started to trust more on their plate armour than in the bulky shield. Even a well crafted gauntlet with some chain mail and leather below could parry or, even better, deflect an incoming attack. The era of the shield was practically over and, although the policemen use it still as riot gear, the protective board was only used to maintain position, but was not for an all out attack anymore. But it is not to say that nobody used it anymore: poor people and commoners were forced to use shields, since this was their only way to protect themselves from the enemy. Only a noble or a rich burgher could afford a good full plate armour.
Coming back to the missing use of the shield, there was still a good way to use it aside from blocking. A soldier could take the rim as a battering weapon, making the shield maybe on of the deadliest weapons. In a good strike the experienced warrior could hit the throat, breaking it despite any protection it may have had and thus killing the victim in a good blow. Many movies fail to mention that element, and usually we only see them used for protection. Movies noteworthy of showing the full functionality of the rim-attack are The Lord of the Rings and 300, though.
In other words, for many sword masters today, and surely in the past, the shield was a weapon, but not a protection. Running over an opponent was easier with a board up front than using just the shoulder and ramming the edge into an arm could break a bone easily. This easily can become part of a fighting style of any warrior in any story. Although this technique was not used much, it still was a surprise attack that the enemy never expected. It may be not game changing in the overall point of view, but life-saving in a moment of need.
Well, I hope you enjoyed this little part of information, and I will see you next post. Please comment if you liked it!
May they smile upon your way!
For further reference:
Contamine, Phillipe (1984), War in the Middle Ages.
Flori, Jean (1988), Chevaliers et chevalerie au Moyen Age [Knights and Knighthood in the Middle Ages].
Various Authors (2007), Fighting Techniques of the Medieval World.