Photomontage is a term applied to a technique of making a pictorial composition from parts of different photographs.Early exponents such as John Heartfield and George Grosz used photomontage for political propaganda.

John Heartfield, The Meaning of the Hitler Salute (November, 1932)
John Heartfield, The Meaning of the
Hitler Salute (November, 1932)

Primary Sources

(1) George Grosz interviewed by Erwin Piscator (1928)

When John Heartfield and I invented photomontage in my South End studio at five o'clock on a May morning in 1916, neither of us had any inkling of its great possibilities, nor of the thorny yet successful road it was to take. As so often happens in life, we had stumbled across a vein of gold without knowing it.

(2) After the Second World War the German poet and playwright, Bertolt Brecht, discussing the origins of photomontage (1949)

John Heartfield is one of the most important European artists. He works in a field that he created himself, the field of photomontage. through this new form of art he exercises social criticism. steadfastly on the side of the working class, he unmasked the forces of the Weimar Republic driving toward war.

(3) Louis Aragon, John Heartfield (1935)

As we know, Cubism was a reaction of painters to the invention of photography. Toward the end of the war, several men in Germany (Grosz, Heartfield, Ernst) were led through the critique of painting to a spirit which was quite different from the Cubists, who pasted a piece of newspaper on a matchbox in the middle of the picture to give them a foothold in reality. For them the photograph stood as a challenge to painting and was released from its imitative function and used for their own poetic purpose.

John Heartfield today knows how to salute beauty. He knows how to create those images which are the beauty of our rage since they represent the cry of the people - the representation of the people's struggle against the brown hangman with his craw crammed with gold pieces. He knows how to create these realistic images of our life and struggle arresting and gripping for millions of people who themselves are a part of that life and struggle. His art is art in Lenin's sense for it is a weapon in the revolutionary struggle of the proletariat.