Night or day the cruisers will have to come uncomfortablly close to the Atoll to spot any thing of value. From a thread I'd posted on elsewhere:
Carl Schwamberger said:
It is certainly a huge equalizer. I was just reviewing the NGF fire support in assorted other landings & in those it is clear the ships were unable to do any precision or timely support without fast ship to shore communications. Even off Omaha Beach the destroyers that came to the surf line had severe difficulty locating the German MG & cannon positions. One officer aboard a destroyer off Omaha described watching a US tank ashore firing for a while & then fired where they guessed the target might be based on impacts of the tanks 75mm ammunition. They could see the 75mm ammo detonating, but not the camoflaged bunker. In many cases they were unable to see the intended target due to it being in defilade, or smoke & haze on the target area. In this case it is clear that point blank ranges of 800 to 1200 meters still had major issues in target spotting by the ships. In the end it required the radio communications to be restored to make the NGF as effective as necessary. Off Salerno a German tank regiment manuvering towards the beach on forward slopes could not be spotted by the NGF ships 5000 to 10,000 meters off shore. Radio comm to spotting teams and infantry CP did lead to accurate fires on the manuvering German Pz Div @ Salerno.
So why is getting close enough to spot bunkers & such dangerous? There is the small possiblity the crusiers wont be aware of how far north of Sand and Eastern islands the reef extends. Its about three nm. If the cruisers apporach from the north and the wind is right they could be onto the coral head before it is spotted. But, that is a long shot. More important is this:
If you can locate a copy of Lt.Col. Robert Heinl's Marines at Midway, June 1942, it contains a pretty good map. The basic organization was:
6th Defense Battalion (Reinforced) – c. 2,130 O&EM
Commanding Officer Col. Harold D. Shannon
Commanding Officer, Eastern Island Group Maj. William W. Benson
Seacoast Artillery Group
Commanding Officer Lt. Col. Lewis A. Hohn
Battery A (2 5-inch)
Battery B (2 5-inch)
Battery C (2 5-inch)
Sand Island 7-inch Battery, Provisional (2 7-inch; manned by Battery B)
Eastern Island 7-inch Battery, Provisional (2 7-inch; manned by Battery A)
Sand Island 3-inch Navy Battery, Provisional (2 3-inch; manned by Battery C)
Eastern Island 3-inch Navy Battery, Provisional (2 3-inch; manned by Battery A)
6th Defense Battalion Antiaircraft Group
Commanding Officer Maj. Charles T. Tingle
Battery D (4 3-inch AA)
Battery E (4 3-inch AA)
Battery F (4 3-inch AA)
Battery G (searchlight)
6th Defense Battalion Special Weapons Group
Commanding Officer Capt. Robert E. Hommel
Battery H (24 .50-caliber MG)
Battery I (24 .30-caliber MG)
Tank Platoon, Provisional (5 M2A4 Light Tanks)
3d Defense Battalion Antiaircraft Group
Commanding Officer Maj. Chandler W. Johnson
Battery D (4 3-inch AA)
Battery E (4 3-inch AA)
Battery F (4 3-inch AA)
3d Defense Battalion Special Weapons Group
Battery K (8 37-mm)
Battery L (18 twin 20-mm on 40-mm carriage)
Provisional Infantry Group
Detachment, 2d Raider (Each company included a weapons platoon of 2 60-mm mortars and 2 .30-caliber M1919A4 MG.)
Company C
Company D
Provisional Marine Companies (Each company included a weapons platoon armed with 2 60-mm mortars, 2 .30-caliber M191A4 MG, and 2 M1916 37-mm guns.)
22d Provisional Marine Company
23d Provisional Marine Company
If you missed it there are six five inch, four seven inch, and sixteen rapid fire three inch long range guns. All of which can reach out over 8000 meters. They also have nice range finding equipment set out on a wide parallax and state of the art fire control computers (analog in 1942, not digital). Best case for the Japanese is they stand off & scatter ammo at the islands at long range. Maybe they hit some aircraft, & if really luck blow up some ammunition. Worst case is they come in much to close, and after opening fire are smothered in a couple minutes by several tons of HE and AP ammo. They may very well not be sunk, but the superstructure damage will be ugly and the internal damage... bad.