The correct answer is that the bombing of Pearl Harbor in 1941 by Japan made American isolationists quickly change their tune as America was under attack. Once Germany declared war on the US, the US was fully into the war.
The Three Emperors League in 1872 was between Alexander II of Russia, William I of Prussia, and Francis Joseph of Austria-Hungary.
The agreement was renewed in 1881 with Alexander III replacing Alexander II of Russia. William I and Francis Joseph remained as signatories.
Becasue they had nothing better to do
