During World War I there were many ’firsts’ and research on male soldiers allowed for the following developments in clincial care:
successful use of blood transfusions in resuscitation
the management of open, contaminated wounds by delayed closure
blood banking
an improved understanding of ’shock’
"The protection of the wounded man against conditions which would develop or increase shock offers, we believe, the greatest hope for his recovery." [2]
motorized ambulances were first introduced for emergency transport.
Care of civilian trauma patients is thought to have been first introduced in Austria in 1925 [1], it was initially designed to treat work-related injuries and then expanded to include all injuries.

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1. Trunkey, D.D. (2000). "History and Development of Trauma Care in the United States." Clin Orthop 1 (374): 36-46.
2. Cannon, W.B. (1918). "The Preventive Treatment of Wound Shock." Journal of A.M.A. 70(9): 618-621.