Speaking just over a century ago about national defense — at a time when he was still fervently engaged in keeping the United States out of World War I — Woodrow Wilson intoned, “While America contains every element of fine force and accomplishment, America does not constitute the major part of the world.”

It was a simple fact in 1916, and remains so, but it’s hard to imagine a politician — much less a president — stating it so baldly today. The “American Experience” documentary “The Great War,” a three-night, six-hour production beginning Monday on PBS, paints a detailed and entertaining picture of the years when America began to think of itself as the major part of the world.