Answer:
While new weapons were created in the hopes to be able to end war more quickly, they instead, were only able to kill enemies more efficiently & more quickly. Especially in World War II, many in fact, served to extend the war. Technology such as machine guns, barbed wire, and mustard gas slowed down pushes to a crawl, and many breakthrough technology such as tanks did not work well. This led to a deadly no-mans land and thousands of miles of trenches to try to protect themselves from enemy projectiles.
So to answer your question, the new weapons were only able to help murder more people more quickly then before.
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