Final answer:
The Eighteenth Amendment, or Prohibition, was necessitated by several conditions including the importance of preserving grain during the war and moralistic sentiments of the nation. State laws had proven ineffective in addressing the issue, leading to the belief that a federal amendment was necessary.
Step-by-step explanation:
The Eighteenth Amendment, also known as Prohibition, was necessitated by several conditions that preceded its passage. One of these conditions was the importance of preserving grain during the war in Europe. The moralistic sentiment of the nation and growing hostility towards all things German also played a role. Prohibition supporters argued that the brewing tradition of German immigrants was un-American and threatened the moral fabric of the nation. Additionally, state laws had proven ineffective in preventing the manufacture and consumption of alcohol, leading to the belief that a federal amendment was necessary to address the issue.