Mobilisation can trap states
Railway plans outran diplomacy in 1914.
The League of Nations, the ILO, and minority treaties were institutional experiments. So were fascism and Bolshevism as answers to the same wreckage.
Votes for women accelerated in several Allied states, tied to war work and sacrifice narratives.
Lessons
Defence can dominate
Technology sometimes favours the holder of ground.
A harsh peace needs power
Paper clauses without enforcement invited revision.
Memory outlives strategy
The poppy now means "war" in English, not only 1914-18.
Empires can win and dissolve
Britain and France sat at Versailles and still lost the twentieth-century imperial argument.
Unresolved
Armenian genocide recognition
Still a diplomatic dispute in some states, settled as historical fact for most scholars.
Reparations myths
Public memory of "Carthaginian peace" often exceeds the cash that actually moved.
Colonial veterans' pay
Unequal pensions remain a live historical-justice issue.
Unexploded ordnance
French and Belgian farmers still meet 1914-18 shells.
Shifts
End of dynastic Europe
Hohenzollern, Habsburg, Romanov, Ottoman -- gone as ruling systems.
US as a great power
Military latecomer, financial giant, then political absentee in the 1920s.
Communist state
The Soviet Union is a First World War outcome.
Middle East state system
Mandates and borders that later wars inherited.
Outlook
Centenary afterglow
2014-18 research boom (digitised unit diaries) is now the new baseline.
Widening the map
Public history is slowly adding Africa, India and the Ottoman fronts to the trench cliche.
A warning, not a script
Great-power war in Europe is not impossible because 1914 happened; 1914 shows how it can start without anyone wanting that war.
Risk
memory and model
The live risk is analogical: leaders still reach for 1914 as a story about sleepwalking. The historical war itself is closed; its memorial form and its peace-failure lesson are not.
Staff colleges taught 1918 as the birth of modern combined arms -- a lineage that runs to 1939-45 tanks and aircraft.
The "never again" of 1918 became the "never again" of 1945 with a bitter rhyme.