The main change that happened during world war 1 was that in the warring countries, the whole nation became one big war factory that produced from ammunition and guns on the one side, to bandages, first-aid equipment on the other, as well as more trivial but sorely needed things such as socks, clothes, etc.
Because a good portion of grown men in this time were at war, it was mostly women and also children, as well as older people, who were working in factories to support their soldiers. They also had to streamline the manufactory process as well as optimize a lot of things because they had to produce much more compared to before.
This was the main way how industry changed.
