"Big Mac" was most surely told that "re-enforcements" would NOT be coming, but I believe he was not told that the resupply would be as minimal as it was in reality. I seem to recall reading that until he was ordered to leave he believed that supplies at least would be sent or were on the way. But in reality they were not in any meaningful fashion. That had been set as policy within a week of Pearl being bombed. When D.D. Eisenhower reported to D.C. to work for General Marshall he was fully aware of the latest Rainbow 5 war plans, whether or not MacArthur was fully aware of them or not is not known to myself.

"…Eisenhower wanted command of combat forces rather than assignment to another staff job, but George Marshall was the highest ranking general and the most respected officer in the U.S. Army. No soldier questioned his orders or tried to have them changed.

"Eisenhower reported for duty in General Marshall’s office on a bright Sunday morning exactly one week after the disastrous Japanese attack on Pearl Harbor. For about twenty minutes they discussed the general situation in the Pacific. With the pride of the Pacific fleet sitting in the mud at the bottom of Pearl Harbor and not enough support vessels available to escort aircraft carriers on long-range missions, the Navy was essentially out of business in that area of the world. The Army Air Force had been largely destroyed in Hawaii and the Philippines. The clamor for ground and air reinforcements in Hawaii and both coasts of the continental United States was urgent, as further Japanese attacks were expected everywhere.

"Ike had never previously talked with Marshall for more than a minute or two at a few military ceremonies over the years. When he thought they were just getting into the conversation Marshall abruptly asked, "What should be our general line of action?" Ike answered, "Give me a few hours." That said, the meeting was over and Ike left to find his new desk.

"Eisenhower did not come to his meeting with General Marshall unprepared to analyze strategic questions and develop practical answers. During his assignment to Panama in the early 1920’s he had been personally tutored on global war strategy for two years by General Fox Conner, one of the Army’s top strategic thinkers. Later, Ike had graduated first in his class from Command and General Staff School and gone on to assignments that required him to examine world-wide military matters, mobilization of armies, and the issues connected with converting the industrial capacity of the nation to a war footing. Perhaps most importantly for Marshall’s first assignment, he had recently spent four years in the Philippines helping to build their military forces and defenses. He was no stranger to East Asia.

"As he knew, the Pacific war situation that mid-December Sunday morning was appalling. The area in peril was 7,000 miles from America’s West Coast and there was neither the transportation capacity nor the naval escort necessary to carry meaningful relief to the American and allied troops in the Philippines, the Dutch East Indies, Malaya, and other vital Pacific posts. There were supply ships and escort vessels being used in the Atlantic convoys to sustain Great Britain, but these were barely enough to do the job. They could not be diverted. All the desktop calculations Eisenhower could do simply verified the fact that the United States could not rescue the thousands of American soldiers defending the Philippines before the unopposed invading Japanese forces would capture the archipelago. Support could be dribbled in by submarine and blockade runners, but the garrisons were doomed.

"Given this awful recognition, Marshall’s question still remained. What should America be doing? Eisenhower used his remaining time with pencil and pad outlining his recommended Pacific strategy. He then returned to General Marshall and advised:

We can not prevail in the Philippines, but we must send what little aid is available. The allied countries might excuse failure, but would never accept abandonment.

Our central strategy should be to open and maintain water and aerial supply routes between the U.S. west coast and Australia. We must build up the ground and air forces that will be required to eventually attack north and recapture the Philippines and other points that the Japanese will have invaded and occupied. (emphasis mine)

"Many high level studies would be done, many meetings with the Joint Chiefs of Staff and the Commander in Chief, President Roosevelt, would be held in the months to follow. But America’s military strategy to make Australia the base for the U.S. Army and Army Air Force response in the Pacific would remain precisely as Dwight Eisenhower envisioned during three hours of thoughtful study on that Sunday in 1941. His many years of study and careful preparation paid off for Eisenhower, for Marshall, and for the United States.


From:

Ike Stories - Ike Sets Wartime Pacific Strategy - Eisenhower Memorial Commission - Ike Sets Wartime Pacific Strategy

Don't forget that when the Trans-Pacific cable was lost after Wake was taken, there was no secure communication line between Washington and Manila. The radio at the time was less than reliable, and code breaking was rampant. Especially against the ancient American codes.

We didn't have CIGABA in place and working yet, that would be later by a few months. That code machine was never broken in its life-time, and was only abandoned in the late fifties when speed of communication became more important.

__________________
Happy Trails,
Clint.