[Suhiir]

I've always found the evolution of the USMC a tad amusing. Prior to WW II it also existed as only brigade (usually regimental) sized units until 1st MarDiv was officially formed in 1941, and was never in the same place until just prior to Guadalcanal.

Post war it was decided to keep divisional formations, but of course with the draw-down and manpower shortages they were so under-strength (less then 65%) as to be a joke. Then came Korea.

Creating the 1st Provisional Marine Brigade in the summer of 1950 took a reshuffling of basically the entire active-duty strength of the USMC. And the 1st Division itself was created with reserves and WW II vets recalled to active duty.

It wasn't really until post Korea "real" divisions continued to exist and even now it's really organized around reinforced and self sustained battalion sized Marine Amphibious Units (MEUs). I'm not sure the USMC has ever done a divisional (or even brigade) sized training other then Command Post Exercises (CPXs), HQ units out in the field but no actual troops.

So while four USMC divisions exist on paper, and can be fielded (the Gulf Wars) when needed, as I've said elsewhere it almost never happens.