By 1. What were the underlying causes of WWI?
They main underlying causes of WWI were nationalism and imperialism. At the time, there was a huge pan-Slavism movement, and many smaller states were pushing for independence and fighting imperialism.
2. What was the specific cause of WWI?
WWI basically started after Archduke Franz Ferdinand of Austria and his wife, Sophia, were assassinated by Princip while in Serbia.
3. How did the soldiers react as they went off to war? Why?
The soldiers were very excited to go off to war. They were told before they were enlisted that they would not have to fight very long, and that they would be well decorated with medals by the time they got home.