This article analyses the young people’s resistance to participate in the war throughout the twentieth century. This resistance was determined by the obligatory participation of citizens in the wars and continued in “peacetime” with the resistance to conscription. It began by the individual resistance for conscience’s reasons, and culminated in a large and heterogeneous social movement that influenced the Government’s decision to abolish the obligatory conscription. To analyze this issue, I selected three European countries: Spain, France and Italy. In all of them, the opposition to conscription had similar motivations among the young refractories; they suffered a strong state repression, which made them deepen even more in their anti-militarism and disobedience that lead to a social movement against the conscription. Finally, resulting from the magnitude of the conflict and their wear, the states opted to professionalize their armed forces.