Misquote, that was never accurately attributed to Orwell. The closest he ever got to saying anything like that was an essay on Kipling where he quoted "making mock of uniforms that guard you while you sleep" from Kipling. Though he once said that pacifists could only be pacifists because of others committing violent acts in "Notes on Nationalism", he's actually speaking against Nationalism and how emotional judgement can cause wars and suffering, particularly in the context of decisions on an international scale.
If you, or whoever made the wall, knew jack about Orwell, you'd realise that wasn't his style. Sorry for the blog post, Orwell is one of my favourite authors and it annoys me to see someone try to tie him to something he wouldn't have liked much.