Pablo Picasso painted his large scale Guernica (1937) in response to the bombing of the Spanish town by German and Italian forces during the Spanish Civil War. Art historian T J Clark discussed Guernica, examining how a work of such enduring political resonance emerged. He looked at the step-by-step creation of Guernica, taking advantage of the set of photographs of the work in progress taken by Dora Maar.
For more info and speaker's biography see this page: http://sydney.edu.au/sydney_ideas/lectures/2011/professor_t_j_clark.shtml