Perhaps the greatest accolade the “Marshall system” received came from an enemy. German Field Marshall Gerd von Runstedt told his interrogators after the was “We cannot understand the difference in your leadership in the last war compared to this. We could understand if you had produced one superior corps commander, but now we find all your corps commanders good and of equal superiority”
Marshall could clear out dead wood in the army's senior leadership because he had a fairly deep bench of mid-career officers mid-career officers who had been educated (and evaluated) in the Army school system. What is often overlooked is that this happy state of affairs owes little to Marshall. Credit goes, instead, to Gen. Douglas MacArthur – the anti-Marshall in many ways.
MacArthur was Army Chief of Staff from 1930-1935 – i. e. in the very depths of the Great Depression. He fought losing battles against pacifists and bean-counters who wanted the Army's budget reduced. With the limited means available to him, MacArthur invested in men instead of equipment:
MacArthur believed that retaining a strong officer corps, even at the expense of weapons upgrades, was essential.
Mark Perry, The Most Dangerous Man in America
As MacArthur explained to Congress as Chief of Staff:
This was a considered judgment; MacArthur was no troglodyte nor was he that stereotypical general who in determined to “fight the last war.”
An army can live on short rations, it can be insufficiently armed and equipped, but in action it is doomed to destruction without the trained and adequate leadership of officers. An efficient and sufficient corps of officers means the difference between victory and defeat.
James P. Duffy, War at the End of the World
As one of his last acts as Chief of Staff he commissioned a study of future military developments. No less an authority than B. H. Liddell Hart wrote at the time "No more progressive summary of modern military conditions and the changes now developing has appeared from authoritative quarters in any army."