The conflict known as the Second Wizarding War, or the Battle of Hogwarts, has begun. The Hogwarts staff are casting defensive charms and evacuating the younger students, while adult wizards over seventeen and graduates have chosen to stay and fight. Eventually, the defensive barriers are breached, and a full-scale battle erupts between the Death Eaters and the students, staff, and others. Ron Weasley is no exception. As a wizard over seventeen and a Gryffindor burning with a sense of justice, he naturally stepped forward to fight.

Ron fought quite well. He took down several Death Eaters within the castle and saved lives. However, in a chaotic moment, a Death Eater's spell missed its target and struck a stone pillar. Ron happened to be standing right beneath it.

...

Immediately after the war ended, although the Death Eaters were defeated, Hogwarts was filled with the sound of weeping and a heavy silence instead of cheers. Among the many casualties, eight red-haired figures were gathered. Ron lay in the center, and his family mourned him in their own ways. Then, ten seconds later, Guest's vision suddenly blurs, and in an instant, the scene shifts back to the noisy battlefield. People are tangled in combat, and in the distance, Ron can be seen swinging his wand, still fighting.