(11th Air Force): A B-17 flies the first armed reconnaissance from the secretly constructed airfield at Unmak , Aleutian over the Aleutian Chain, but finds no sign of the enemy. XI Fighter Command elements are not deployed at Unmak (P-40′s and P-38′s), Cold Bay (P-40′s), Kodiak (P-39′s), and Elmendorf Field [P-38's and Royal Canadian Air Force (RCAF) Kittyhawks].
USA - Secretary of War Henry L. Stimson warns Americans along the west coast to expect a Japanese attack as retaliation for the Dolittle raid on Tokyo.
SOUTHWEST PACIFIC AREA (5th Air Force): B-26′s attack the airfield at Lae, New Guinea.
New Hebridies – U.S. forces arrive at Espiritu Santo.
Pearl Harbor, Hawaii:
USS Enterprise, Hornet and escorts have sortied to meet the Japanese fleet bound for Midway. USS Yorktown, which arrived 27 May from action in the Coral Sea is in the shipyard undergoing desperate repairs to enable her to join Enterprise and Hornet.
In an inauspicious beginning, perhaps future, LCDR Lindsey, CO of VT-8 crashed astern of Enterprise while flying aboard Enterprise. He and the rest of his crew are rescued by the planeguard, USS Monaghan.
While Yorktown is in dock, her airwing receives new aircraft and performs maintenance on the others.
After clearing the Inland Sea on the 27th, Nagumo’s forces have set a north-easterly course at 14 knots. Ships crews turn to the daily routine of maintenance, cleaning and participating in drills while the embarked aircrew amused themselves playing cards in the ready room or passing around novels while sunning themselves on the flight deck – some had brought wooden deck chairs for this purpose. (ed – It would appear there were (are) some universal similarities across naval aviation…). The overall mood of the crews was relaxed. Duty carrier rotation was set with Soryu taking the first watch on the 27th. However, overnight on the 27th, CDR Fuchida Mitsuo, CAG for Akagi’s air group, was diagnosed with acute appendicitis. Although he pleaded otherwise, the flight surgeon overruled him and operated immediately. Fuchida would miss the coming battle, at least leading the air group in battle, and this was dismaying to the veteran crews.
1430, 28 May – Kido Butai’s supply ships are sighted and once they were joined in the force, a course change to east-northeast was ordered. Speed remained at 14 knots in consideration of the destroyers and other fuel hogs in the fleet.