It is also a walk from conventional to unconventional warfare, from a Eurocentric world driven by realpolitik in 1914 to a multipolar world driven by economics and ideas in 2008.
The Great War and its sequel of 1939–1945 made battleships obsolete. Mobility and cover in the form of submarines and aircraft carriers changed naval warfare, just as airplanes and tanks changed the mode of land combat. Total war between industrial states changed the global balance of power and the mindset of humanity.
Ninety years later, we are still struggling with the legacy of 1918. Traumas like the Second World War and the Cold War tend to obscure the defining moment of the modern era, the ultimate cataclysm that turned Europe into what the Czech politician Thomas Masaryk called a "laboratory atop a vast graveyard".
After an historical parenthesis between 1989 and 2001, we see many of the ghosts of the 20th century returning: the oil crisis, inflation, ...