1. Diplomacy became increasingly constrained by a hardening system of alliances, the politics of nationalism and imperialism, and domestic demands, leading to an unwanted war that nevertheless served as a unifying force for societies under strain.

2. By the end of 1914 the struggle turned into a long war of attrition supported by massive extension of governmental control.

3. Leaders of the Paris Peace Conference, facing conflicting interests, produced treaties that supposedly would reflect the optimistic liberal ideals of the Allies, but which nevertheless outraged some and left all dissatisfied.

4. After an early period of some instability, most European nations followed a democratic path during the 1920s.