Why the allied powers pinpointed Germany at the person guilty for starting world war 1

the answer is that Archduke Ferdinand of Austria, assassination started it with chain events that led to war the person who killed archduke ferd was Gavrilo Princip which he was in the Serbian-nationalist terrorist group called the Black Hand

Explanation:

besides the fact that abraham lincoln abolished slavery, and greatly benefit black people, he had a heavy impact of the definition of what democracy was, and should be.