I've always wondered how an infantry soldier, without a pike (which cavalry wouldn't charge into normally), deliver a fatal blow to a Cataphract?
What I know is that Cataphracts were used as heavy shock troops that were used to break enemy lines. After they smash into any unit, some sort of hand to hand fighting would take place.
What I want to know is how during that fight, a cataphract knight could be killed. In other words, how would an infantry soldier overcome difference in height, weapon reach and maximal armor with little holes and deliver a fatal blow?
There are many forms of armor for Cataphracts across history, but they all were very heavily armored. Persian/Sassanian Cataphracts riders' heads were even entirely armored. I can't imagine a swordsman or a spear-man being able to deliver a fatal blow when faced with such a fearsome opponent.
Any idea or historical evidence of how very heavy cavalry were defeated?
During the course of history, many battles took place where armies composed/contained Cataphracts were defeated, such as:
In the Battle of Tigranocerta, a small inferior Roman force defeated an Armenian force with some Cataphracts, by flanking them and attacking their rear.
In the Battle of Yarmouk, the brilliant Khalid managed to beat the Byzantine cavalry with his much lighter cavalry, again by superior tactics. He managed to beat Persian armies that had heavy cavalry too at many other occasions.
Alexander crushed the Persians (Granicus, Issus and Gaugamela) with their superior heavy cavalry, by using a clever combination his Macedonian pikemen and his personal Companion cavalry.
All the battles and sources I can find states that the heavy cavalry were defeated by superior tactics and flanking. However, I cannot find any reliable source stating the defeat of a Cataphract in a hand to hand fight.
Following the excellent answer by @Mynott95, I was recently reading about the Battle of Strasbourg also known as Battle of Argentoratum between the Western Romans and the Alamanni confederations. It describes how the Germans dealt with the heavy Roman cataphracts head on:
The Roman heavy cavalry now charged the German horsemen. In the ensuing mêlée, Chnodomar's stratagem paid dividends. The interspersed foot warriors wreaked havoc, bringing down the horses of the cataphracts and then killing their riders on the ground.