World War One is definitely a major turning point into the modern age: the millennia-old dominance of horse cavalry was definitively ended, and the mechanization of warfare (and the industry that supported it) were clearly rising to dominance. The Battle of Cambrai is, to me (and probably many other historians and historically-minded people) a “turning point within the scope of a larger turning point”: America started to become a key player and experimented with expeditionary military-projection capabilities, and at Cambrai the first halting steps to forming “combined arms” doctrine was taken. Of course it wasn’t called that, but an attempt was made to integrate tanks, infantry, artillery and air power into a one massive, coordinated battle.
The old world had truly come to an end; World War One was its tombstone and the herald of the future. It has been one hundred years since this pivotal event in history… it’s hard to believe that with the last of the veterans passing just a few years ago, this is no longer an even that exists within living memory. Lest we forget.
Researching the slang for this was fun, “Jack Johnson” was a champion American boxer and African-American; it became the slang term for an air-bursting flak type shell that would beat you as soundly as the heavyweight champ. “Pear Drops” was trench slang for poison gas. “Mutt & Jeff” was the pair of British “war” and “victory” medals awarded to soldiers that completed their service, and “Order of the Bowler Hat” was to turn in your military helmet for a bowler hat and become a civilian again. All this is incomprehensible to the modern troops, since this slang exists in its time as surely as the memories of the veterans who served in it.