War and art

Many artists, intellectuals and writers welcomed the outbreak of the First World War. They saw it not as an apocalypse but as the opportunity for a change for the better. As such they joined in the patriotic fervour of the first weeks and months of the war. What motivated them not only to devote their artistic energies to the fatherland but also to take an active part in the fighting? How were anti-war sentiments articulated by artists? What other forms of relationship were there between art and warfare during and after the First World War?