July 6 1944: Marshall notifies MacArthur: "Arrange your plans so as to arrive in Honolulu July 26th . It is of utmost importance that the fewest possible number of individuals know of your expected departure or of your destination.”
July 18 1944: Marshall informed MacArthur to "proceed as directed" and that no further orders were necessary. "Purpose: general strategical discussion," cabled Marshall. "I will be in Washington but you will see Leahy, etc. In communicating notice to Army theater commander of arrival time your plane refer to yourself as Mister Catch." **
Source: (Marshall to MacArthur, Radios, July 6 and 18, 1944, GCMRL/G. C. Marshall Papers [Pentagon Office, Selected].)
** = MacArthur not specifically told he was to meet FDR in Hawaii.