What caused Bulgaria to enter World War 1?

Answer 1

Bulgaria wanted to regain land lost in the second Balkan war from Serbia and later Greece and Romania. When the war broke out Austria-Hungary and Germany made better offers to Bulgaria regarding this lost land and the Pro-German government declared war.

Answer 2

Gavrilo Princip out of the Black Hand from Serbia and two other Black Hand members shot and killed the Archduke Franz Ferdinand and his wife of the Austro-Hungarian empire in Sarajevo. The Austro-Hungarian empire responded by invading the Kingdom of Serbia and starting World War 1.

Answer 3

Bulgaria entered ww2 because of the treaty it had with Russia. Russia and Bulgaria were side by side and their treaty had not yet ended. as a result, Bulgaria was to some extent forced to join the war otherwise it would be under extreme threats from Russia
With the HOPE that it could restore its lost territory during Balkan wars and WW1. And to avoid San stefano treaty and Berlin treaty (Bulgaria thought these treaties were unjustified and imposed to it).

Answer 4

To recover its lost territories before Balkan wars I and II
to try to reclaim its lost territory in Balkan wars