Does the propaganda posters full explain why men wanted to join the army?

Yes. Men went to war for three reasons. For the Money, the Fame and the Pressure. They would be paid considerably more than their average job, they would become famous and they would be pressured into it by the media. Guilt was the main weapon. If a man feels guilty after letting Britain, after letting his country down, he will definately join up, to protect not only their country but also it's citizens. All because of a single poster.