"It was Guatemala, " wrote Guevara's first wife Hilda Gadea, "which finally convinced him of the necessity of armed struggle and for taking the initiative against imperialism. By the time he left, he was sure of this."
- Stephen Schlesinger and Stephen Kinzer: Bitter Fruit: The Untold Story of the American Coup in Guatemala. (Anchor Books 1983) p. 184
Assuming it's an option, the answer is most likely the Magna Carta, signed by King John at Runnymede following his defeat at the hands of the English lesser nobility during the First Baron's War.
