It's true there are certain mechanisms in a democracy to put brakes on a rush to war. This presumes that the people at large value peace, which is true to a certain extent. People know that war is hell, and in a society that has a full-scale democracy (that is, few factors to obstruct liberal democracy), people are going to favor no war over war, up to a certain point.
Your example about WWI does show that democracy can be undermined by war, but remember that the wheels of American democracy turned as hard as they could to prevent a declaration of war with Germany (we gave them every possible excuse to butt out, but they sent persistent signals that they already considered us enemies to a certain degree, including the Zimmermann telegram)
Monster Hunter: pissing me off since 2010.
