Okay, let's pretend you're playing pretend games and you're pretending to be someone from a long time ago, like your great-great-grandparent.
A long time ago, there was a very big war called World War I. A man named Lord Kitchener was in charge of getting some people to help fight in the war. And he really wanted people to help out - so much so that he made a poster with his picture on it, pointing straight at you and telling you he wants you.
The poster was put up all around the country to encourage people to help out in the war effort. So, if you were around back then, you might have seen the poster and known that Lord Kitchener really needed you to help him.