This famous image of General Kitchener was one of many propaganda posters used to encourage normal working men to join the army.
This poster shows normal men from all different trades lining up to join the army and then it shows that they all become soldiers. This implies that anyone who was able-bodied should enlist.
As the war continued much longer than expected, and the death toll continued to rise, the government took action to make it a law that only a few could be excused from joining up.
These were the trenches. Imagine living in these for months at a time! This is where the soldiers slept, ate and had social time. They were under constant threat of attack in what was basically basically their home. How awful!