Centelles is considered one of the pioneers of modern photojournalism and to him we owe the best photographs of the military uprising in Barcelona on 19 July 1936. His pictures are amongst the most representative and famous of the Spanish Civil War, whether of the rearguard in Barcelona, the bombing raids in Lleida, the Aragon front or the period in the Republican refugee camps in France. He was called up in 1937 and immediately called to the Commissariat of Propaganda, who put him in charge of the photography section of the State Department of Information. From then on, his magnificent photographs of the Aragon and Lleida front were distributed by this institution.