Who was the richest person in the world when the World war II started and when it ended? Was it the same person? If so, how did the war years affect his wealth?
John D. Rockefeller Sr. was far and away the richest man in the world in 1937 at his death. But with the bulk of his wealth bequeathed to the Rockefeller (and other) foundations rather than to his son John D. Jr., that probably leaves Henry Ford the world's richest man in 1939.
However Ford had suffered a number of strokes in the late 1930's, and when he resumed active direction of the company in 1943 after Edsel's death, gross mismanagement led to horrendous monthly losses and his ouster in 1945. As the largest customer of the Ford Motor Company during those years was undoubtedly the American military, one might almost say that despite his virulent and infamous anti-Semitism, Ford personally financed a more rapid defeat of Nazi Germany.
There are numerous lists on the web listing the Wealthiest persons in history, all with slightly varying estimates of the order and composition, but all place Ford high on the list. The contemporaries who contested his position - Vanderbilt, Carnegie, Mellon, and Rockefeller - had all preceded him to the grave, bequeathing their vast fortunes to foundations.
Here is the very first Forbes Rich List, from 1918, which lists the richest 30 Americans of that date. It is very likely that the wealthiest individuals up to the early 1950's can trace much of their wealth back to this list, due to the world-wide effect of the Great Depression and the accompanying deflation.
According to Seagrave's book, Gold Warriors, the richest man at the end of WWII was presumably the Emperor of Japan. Japan had spent the previous 50 years looting and pillaging various territories. It is believed at least a third of the war loot had been brought back to Japan by the end of the war. Other parts of the war loot was discovered by the Americans and used to set up the "Black Eagle Gold Trust". Is there a connection decades later to 911?