The First World had conscription on nearly all sides after willing volunteers ran out.
However, for some people, the whole idea of war was wrong. They refused to fight in the war, preferring to go to prison rather than compromise their beliefs.
Some played a valuable part in helping the wounded in No Man's Land. Others refused to take part in that, arguing they would be helping to prolong the war by fixing people up.
It sometimes takes more courage not to fight than it does to fight. If I had been around at the time, I suspect I probably would have gone to war. I was briefly a pacifist, but lost that a long time.
Sadly, it is sometimes necessary to go to war- it will be until the Second Coming. But I respect those who disagree provided they are genuine about it and not biased in who they criticise.
Don't buy white poppies- the money does not go to help those who have been injured. If you don't want to wear a poppy for whatever reason, just put a quid in the poppy box. It still helps people.