Who said "War teaches you everything about yourself."?

This quote is attributed to Arrow.

War teaches you everything about yourself. - Arrow

"War teaches you everything about yourself."

Arrow War

"My name is Oliver Queen. After five years in hell, I have come home with only one goal: to save my city."

"I'm not the man I was."

"You have failed this city."

"I'm a monster."

"Some battles are worth fighting."

"Sometimes you have to become the monster to stop the monsters."

"Skynet sent me back through time to kill you."

"War teaches us the value of peace."