The stove shield, heater shield

The heater shield, triangular shield or heater shield was used from the late 12th century to the late 14th century. It is the typical shield associated with the age of chivalry. Shields of this type were worn by both infantry and cavalry and were often painted with heraldic motifs.

The name "heater shield" is a neologism coined by Victorian historians because the shape resembled an iron. The shield is also sometimes called a triangular shield or a heater shield. 

The heater shield, is a type of medieval European shield that originated in the late 12th century from the larger Norman kite shield . The reason for this development was possibly that body armor improved, making the protection of a large shield less important. The heater shield is significantly less massive than its predecessors but still retains the same characteristic shape. Shields of this type were used by both cavalry and infantry. Examples of this type of shield can be seen on the great seals of Richard I and John, King of England.

The heater shield was smaller than the kite shield, making it easier to handle and use on horseback or on foot. From the 15th century, it evolved into specialized tournament shields, often with a "bouche," a notch through which the lance could pass. As armour covered more of the body, the shield became smaller. By the mid-14th century, it was almost no longer used outside tournaments.

Heater shields were usually made of thin wood with a textile or leather layer over it that protected the wood from impacts and made it extra tough. Sometimes the wood was reinforced with steel or iron. Some shields, such as that of Edward, the Black Prince in his tomb in Canterbury Cathedral, had extra layers of gesso, linen, and/or parchment.

Contrary to popular belief, the shield was not attached to the arm. It was held and moved with a hand strap and a belt called a guige. This went around the neck and supported the shield, and could also be worn over the back when not in use. The carrying technique can be compared to the older kite shield. 

The heater shield was used by almost all ranks within the army of the High and Late Middle Ages. The shield was popular with both the knightly class and the infantry. This type of shield also had disadvantages. When used correctly, the legs were almost not protected at all. This disadvantage could be mitigated by moving away from an opponent. As an old instruction says: "If a sword goes for your leg, strike at his face or throat: his arms will tire faster than his head." This assumes that an opponent has to cover a longer distance to reach your leg with his weapon than you need to reach his head, throat, or shoulders with your weapon. Unfortunately, there are hardly any historical sources on how exactly fighting with heater shields and sword was done; the known fight books all date from a later period.