Complex sentence: She understood that the First World War had played an important role in broadening the appeal of women's suffrage because the manpower shortages required widespread female employment, making the image of the sheltered female more obviously inapplicable to Canadian circumstances.
Split into simpler sentences: She understood that the First World War had played an important role in broadening the appeal of women's suffrage. The manpower shortages during this time required widespread female employment, making the image of the sheltered female not applicable to Canadian circumstances.