re: History Nerds: Which U.S. military commander least deserved his fifth star?

MacArthur's biggest sins were

1 letting his air force get destroyed on the ground despite having advance warning of an imminent attack; a blunder that would be repeated in Korea when he ignored intelligence reports of Chinese troops massing along the border

2 neglecting to move supplies into the Bataan peninsula in a timely manner

3 failing to split his command when he evacuated. After Bataan fell, Mindanao was still combat effective but being in Wainwright's chain of command, had to surrender when he did. With an independent command, they could have resisted several more months