How did children contribute to WWI?

Since during the war a lot of men (and even women) fought on the battlefield, there was a need to somehow compensate the work of labor force on factories and other places, in order to maintain the economy and production on the levels sufficient for the country's survival and competitiveness. Therefore, many companies had to go against the laws prohibiting child labor, and used children as workers. Mostly, children worked in the spheres directly connected to manugacturing arms and ammunition, although it was not uncommon for children to work in other areas as well. Influenced by propaganda, a lot of teenagers falsified their age in order to be able to enroll into the army.