A 50/50 cast of males and females played the roles of soldiers and nurses who gave their lives to fight for their country, in the performance titled A Century to Remember.
"It was the collective story about sacrifice, the idea of service above self," Mr O'Grady said.
Pupils showed it was difficult for young people today to empathise with those hardships, by using a clever flashback from a colourful modern-day classroom to war scenes presented in greyscale.
Event manager Sarah-Jane Phillips said: "Karamu High School blew us away.
"They gave 100 per cent in each move they did. From start to finish, I was captivated," Ms Phillips said.
Judges were impressed by the effective use of light versus dark, created with make-up, costume and props.
Taradale Intermediate took out second spot with their performance of War Games, while Napier Girls' High School came in a close third.
"Napier put on a fantastic show tonight and I was blown away by all the students' talent and hard work.
"Performances reflect how Stage Challenge and J Rock are great outlets for youth to creatively express themselves and their values," Ms Phillips said.
It also promoted positive role models by supporting a 100 per cent drug, alcohol and tobacco free event, she said.