"The only thing we learn from history is that we learn nothing from history."
George Bernard Shaw, The Revolutionist's Handbook
It probably doesn't matter to those killed in the Korean and Vietnam wars that Western Civilization has enjoyed the second longest period of peace in history; but it is so. Since 1945 there have been minor conflicts but no major wars among the western powers.
The last era of extended peace was under the Roman Empire. It is usually called the Pax Romana; it might with as much justice be known as the Peace of the Legions.
The legionnaires of that time were career soldiers, liable for duty anywhere on the frontiers. They built their camps in the afternoon, and destroyed them the next morning, seldom staying in one place for long. They could look forward to permanent settlement and perhaps their own small plot of farmland when they retired; not before. Their life was hard, but they protected the peace.
Like all soldiers throughout history, the legionnaires would take any benefits the government offered. Successive candidates for Emperor offered; and eventually the legionnaires came to believe that soldiering was more a matter of accumulating rights than discharging duties.
That road led to the fall of Rome, an event that still dominates much of Western history. Rome still dictates our ideal of what the world should be: a place of quaint diversity, but united by a common language, and sharing a common set of basic rules of decency.
Cyril Kornbluth was a veteran of the Battle of the Bulge, where he received the injuries that ultimately killed him. Kornbluth's reflections on the only thing we learn from history were written shortly after that War.