Janab-e-Qasim (as), the son of Imam Hasan (as), and the nephew of Imam Hussain (as)
Qasim (as) was only 13 years old, barely in his teens just like his cousins Aun (as) and Muhammad (as). The bond between nephew and uncle was extremely close. Since the day Imam Hasan (as) was poisoned and killed, Imam Hussain (as) treated him like his own son.
On the 10th of Muharram, Qasim (as) was eager to step into the battlefield, but Imam Hussain (as) wouldn't give him permission. He (as) would say, you're a constant reminder of my brother, you're the only child of your mother, how can I let you go and die? When he didn't get permission despite insisting, he went to his mother, Umm-e-Farwa (as), crying. He (as) told her his uncle wouldn't let him fight. Bibi Umm-e-Farwa (as) reminded him of the amulet his father (as) had given him on his deathbed. The Imam (as) had instructed his son to open the amulet when he is in desperation. Qasim (as) took the taveez to his uncle (as).
The amulet read, 'Hussain, a day will come when you'll have to make great sacrifices to save Islam. I will not be alive on that day. However, Qasim will be there. It is my wish that he represent me on that day."
When he (aa) read this, both the Imam (as) and Qasim (as) began to cry. He (as) took his nephew to Bibi Zainab's (sa) tent, and asked her to bring Imam Hasan's (as) cloak and turban. When he was dressed, Imam (as) looked at him and said you look just like your father. Narrations mentioned that at this moment they hugged each other and cried so much that they passed out and fell on the ground.
Hazrat Abbas (as) helped him mount his horse because he (as) was too young to do it himself. His feet did not even reach the stirrups, and when he (as) walked, his sword touched the ground.
He (as) rode into the battlefield and fought gallantly. The enemy could not overpower him from the front, so they decided to attack him like cowards from behind. Someone struck his head with a sword and he (as) fell from the ground.
On ashura whenever someone fell, they called out, 'come to my aid my Imam', regardless of their relationship. But Qasim (as) and Hussain (as) were so close to each other that when he (as) fell, he (as) called out 'come to my aid o uncle'.
What followed this call is one of the most brutal scenes of Karbala. Hazrat Abbas (as) rushed towards the army from one side, Hazrat Ali Akbar (as) from another side, and Imam Hussain (as) from a third side, all to come to the aid of Qasim (as) .
This resulted in the enemy descending into complete chaos. They began to retreat, and in doing so, their horses ran over the body of Qasim (as), their hooves trampling his body. By the time the Imam reached him, Qasim's (as) body was scattered on the ground in pieces. Such was the case that Hussain (as) had to take off his cloak, pick his nephew's torn body piece by piece, like picking flowers from a garden, and carry them with him in his cloak like a sack.