How did the CIA-assisted overthrow of Jacob Arbenz solidify Guevara's political stance?

"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