The invention of the typewiter provided a means by which women could gain access and entry into the heretofore exclusively male world of the business office. World War I and World War II provided additional office work opportunities for women in the labor force due to the vast number of men in the military. Also, within military, a large area of employment was opened with the formation of the women's service branches-a large part of which consisted of office work. Over the years there has been an increase in the number of women employed in office work.