What were the dangers of the secret treaties in world war 1?

The intricate web of alliances meant that once the assassination of Arch Duke Ferdinand took place, the Austro-Hungarian Empire sent an untimatum to Serbia, Russia came to Serbia's defense; Germany stood against Russia; France stood against Germany. When Germany swept through Belgium to attack France, Britain declared against Germany. So, you can see how the network of alliances spiraled out of control in very short time.