According to Eric MetaxasDietrich Bonhoeffer and Frenchman theologian Jean Lasserre went to the movie, All Quiet on the Western Front in 1930. This movie apparently had a profound impact on Bonhoeffer.

The sadness of the violence and suffering on the screen brought Bonhoeffer and Lasserre to tears, but even worse to them was the reaction in the theater. Lasserre remembered American children in the audience laughing and cheering when the Germans, from whose point of view the story was told, were killing the French. For Bonhoeffer, it was unbearable. Lasserre later said he could barely console Bonhoeffer afterward. Lasserre believed  that on that afternoon Bonhoeffer became a pacifist. 

(Bonhoeffer, Pastor, Martyr, Prophet, Spy by  112-113).