This chapter explains the repertoire of actions brought about by the mobilisation of minds. As numerous historical works have underlined, the war was not a monolith, and it aroused among the belligerents phases of demobilisation and remobilisation. Cultural engagement was subject to great chronological, national, disciplinary and individual diversity. Intellectual mobilisation was not unchanging throughout the war, but displayed both chronological and national heterogeneity, occasionally among the same individuals. If citizens were aware of entering into a national conflict comparable to those of the nineteenth century, from the outset they also attributed to it a greater ideological value. Resistance to the war was confined to the margins of intellectual life. Restricted as it was, there was nevertheless an intellectual camp that acquired dissident status in the face of the overwhelming consensus and that assumed various postures of protest against the war and those who waged it.