Answer: World War I.
Step-by-step explanation:
When we talk about collective opposition to war, we can take World War I as an example. The beginning of the conflict in Europe and the world met with collective opposition to the entry into the United States' war by the people and the government. President Woodward Wilson himself was opposed to the country entering the war. The people supported him with slogans that could be seen across America in those years and read "The One Who Saved Us from the War," alluding to the president. The United States joined the war only near the end of the conflict when its interests began to be threatened. Globally, the people and the government were against involving the country in the war.