The Civil War had a profound effect on everyone in the United States. With most of the men out fighting, the women wanted the opportunity to show support and gratitude for the soldiers. There are no concrete figures, but some historians estimate that up to 10,000 women became nurses to help the cause. Many were volunteers, but they wanted the opportunity to prove women were strong enough and smart enough to work under the most horrific conditions.
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eHow Article: About Nurses During the Civil War