Even before these Japanese plans were made, and long before
Admiral Yamamoto sortied eastward, all U.S. military planners
recognized the vulnerable position of the Midway Atoll.2
Especially was this position clear in the light of early
Japanese successes elsewhere in the Pacific, and none was more
keenly aware of the grim situation that the atoll's small
garrison force. The 12 PBYs of VP-21 were soon withdrawn, and
little help was expected from the crippled fleet. But on 17
December, while the 6th Marine Defense Battalion worked to
improve existing defense installations, 17 SB2U-3s (Vindicators)
of Marine Scout-Bomber Squadron 231 (VMSB-231) flew in
unexpectedly from Hawaii. Led by Major Clarence J. Chappell,
Jr., and assisted in over-water navigation by a PBY, the
obsolescent craft made the 1,137-mile hop in nine hours and
twenty minutes.3 Other reinforcements, including about 100
officers and men of Batteries A and C of the 4th Defense
Battalion, left Pearl Harbor on 19 December with the old Navy
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