[Tallguy]

Not only wasn't MacArthur sacked, technically he was recalled to duty. I believe that Douglas MacArthur was on the retired list while serving as military advisor to the Philipines.

The answer is probably that MacArthur was politically well connected, having been a former army chief of staff. Plus the whole concept for the defense of the islands was to fight a holding action from Bataan & Corregidor and await relief from the Fleet. With Pearl Harbor, relief was not to be expected. Whatever else we may think of MacArthur, he at least did his job.

[Tallguy]

Correction: MacArthur was not retired from the US Army but he was serving in the capacity of Military Advisor to the President of the Philippines. Later on in 1941, he was given authority over all US Troops then serving in the islands.