During the trial, he said that he was a Yugoslav Nationalist. That he aimed to unite the yugo slavs. But it didn’t matter to him which state would Yugoslav be a part of. But during the trials, he wanted that Bosnia should be free from Austria. The emperor of the Austro-Hungarian empire is enraged at the assassination.
In his anger, the declares war on Serbia. Russia sees this as an attempt to annex Serbia. And so Russia went to save Serbia. Germany saw that Russia was taking arms against the Austro-Hungarian empire. And so Germany went to save the Austro-Hungarian empire.
This time, France doesn’t stay behind. France reached there in support of Russia and Serbia. This created an interesting chain called the Chain of Friendship. This is an interesting caricature drawn to describe the situation.