As men left home to fight in the war, women were needed to replace them. How many women joined the labour-force during the war?

Before the World War One, women were restricted in their employment opportunities.  Many jobs were forbidden to women, their pay was much less than that of men and they were not entitled to vote.  By the war's end life had improved somewhat, but there was still a long way to go before women and men would be considered as equals.