At Surigao Strait, three battleships did the majority of the shooting: West Virginia, California and Tennessee. All three ships had received total reconstructions during the war and installation of Mark 8 fire control radar. A fourth battleship contributed meaningfully: Maryland, refitted before the war and fitted with Mark 3 fire control radar during the war. Also present were Mississippi and Pennsylvania. Mississippi received a total reconstruction before the war and was fitted with Mark 3 fire control radar during the war. Pennsylvania received an extensive refit during the war and was fitted with Mark 3 fire control radar. Mississippi managed only one salvo during the engagement. Pennsylvania failed to fire.

That the Mark 8 Fire Control Radar (FCR) was superior to the Mark 3 FCR is neither a mystery, in contention, nor a surprise. That Maryland was able to get on target and fire six salvos while her Mark 3 fitted compatriots did not is more interesting. Why was Maryland able to do this?

A simple explanation is crew proficiency. It is entirely possible Maryland simply had a more experienced and/or talented radar and gunnery team than the other two Mark 3 battleships. But there's probably more to it than that. A clue lies in the explanation commonly given for Maryland's achievement: she ranged off West Virginia's shell splashes. Another clue lies in the geometry of the engagement.

The battle line started the action at 0348 steaming course 090 at 15 knots in the following order at 1000 yard intervals: West Virginia, Maryland, Mississippi, Tennessee, California and Pennsylvania. Length of the line was 5000 yards. At 0355 all six ships simultaneously turned right to course 120, proceeding in parallel to the southeast. At 0402, all six ships again simultaneously turned right, this time to course 270. By 0406 they completed this turn and were proceeding in reverse of their original heading and in reverse order: Pennsylvania, California, Tennessee, Mississippi, Maryland and West Virginia.

Roughly 6500 yards south of the battle line was the eastern cruiser line steaming course 092 at 10 knots in the following order at 500 yard intervals: Louisville, Portland, Minneapolis, Denver and Columbia. Length of the line was 2000 yards. From 0348 to 0409, the eastern cruiser line maintained its course and speed, executing a simultaneous turn to port (north) at 0409.

Thus, at the start of the action, the rears of both lines were almost abeam each other, meaning the cruisers masked Tennessee, California and Pennsylvania, but not West Virginia, Maryland and Mississippi. As the two lines moved to the east on roughly parallel courses, the battle line began to pull ahead of the cruiser line until 0355 when the battle line turned to 120. The difference in speed roughly maintained the relative positions of the last three battleships, the five cruisers and the target battleship, Yamashiro. Thus, Pennsylvania was masked throughout this period, but neither Mississippi nor Maryland was masked. However, none of these ships fired during this period.

At 0355, the turn to 120 caused the battle line to stop "running away" from the cruiser line and the relative position of the cruiser line began to move up the battle line. However, the cruisers did not "clear the range" for Pennsylvania (the last battleship) until roughly 0402, when the battle line commenced its turn to 270. As the battleships progressively turned to the rough reciprocal of the cruisers' course the cruisers steadily unmasked more of the battle line. By roughly 0405-0406 the Mississippi, Tennessee, California and Pennsylvania all enjoyed a clear range and only West Virginia and Maryland were masked. By "cease fire" at 0409 the entire battle line was unmasked.

Based on this motion analysis the Maryland, Mississippi and Pennsylvania probably enjoyed the following range conditions: Maryland: Unmasked 0348-0400. Masked 0400-0408. Unmasked 0408-0409. Mississippi: Unmasked 0348-0356. Masked 0356-0406. Unmasked 0406-0409. Pennsylvania: Masked 0348-0402. Unmasked 0402-0409.

From 0348 to 0351, neither the cruiser line nor the battle line fired. During this period both Maryland and Mississippi should have had an unobstructed visual and radar line of sight to Yamashiro. Pennsylvania would have had to contend with the cruisers' visual silhouettes, but proper employment of the radar should have eliminated any spurious returns from the cruisers.

At 0351, the cruiser line opened fire and maintained fire until "cease fire" at 0409. Throughout this period the flash of the cruisers' firing could foul the visual range of any masked ships.

At 0353, the West Virginia opened fire, followed by Tennessee and California at 0355 and Maryland at 0359. Mississippi fired her sole salvo at "cease fire," 0409.

West Virginia opened fire two minutes prior to a simultaneous turn right 30 degrees to course 120. Tennessee and California opened fire while executing that turn. Maryland opened fire while on course 120. Mississippi fired her single salvo on course 270.

At the other end of the engagement, the Yamashiro was roughly on course 020 from 0353 to 0356. At 0356 she came left to roughly course 265, steadying up briefly at ~0400 and then gradually arcing more southerly until 0409 at which time she executed a roughly 90 degree left turn to course 170 on which she staggered until she capsized at 0419.

Throughout most of the period from 0353 to 0359 the American battleships were within an arc from 10 degrees right of Yamashiro's bow to about 5 degrees left. Thus Yamashiro was presenting a very narrow visual and radar target to the battle line. From 0359 to 0409, the Yamashiro's left turn gradually expanded the visual and radar target to maximum (when Yamashiro was beam-on in her turn) until the American ships were placed roughly 30 degrees abaft Yamashiro's starboard beam, still a very good visual and radar target with Yamashiro presenting three large areas of vertical development to vision and radar (foremast, funnel and mainmast).

What all this means is that for 12 minutes Maryland had an unobstructed visual and radar line of sight to the target at the start of the engagement. However, Maryland did not open fire until 11 of those minutes had passed and only 1 minute before being masked. Mississippi had 8 minutes of unobstructed line of sight to the target but did not open fire. Pennsylvania was still masked.

Why did Maryland wait so long to fire and why did Mississippi not fire? Probably for two reasons: 1) At over 22,000 yards at night the Yamashiro was probably largely invisible from head on to the eye. 2) Beginning at 0353 the Yamashiro was probably localized by, but obscured within, shell splashes.

From 0353 to 0356 Mississippi had an opportunity to localize and acquire Yamashiro by spotting the fall of shells from the three Mark 8 battleships, but she failed to do so. Why? Probably because during this period she was almost directly ahead of Yamashiro and so presented with Yamashiro's narrowest profile.

Meanwhile, Maryland enjoyed an extra three minutes and a better vantage point farther to the east presenting more of Yamashiro's profile...but not much. Thus from 0353 to about 0355 Maryland's radar operators probably took note of the transients of West Virginia's shell splashes and began to prepare to shoot. But at 0355, I suspect they lost any potential hard return in the increased clutter of splashes as Tennessee and California joined in. This probably blinded Maryland's operators for a minute until Yamashiro started turning at 0356. The shell splashes told her radar operators where to look but obscured the radar target Yamashiro was presenting. As Yamashiro began turning, she progressively presented a larger and more distinct radar target to Maryland and her operators were probably then able to pick out the "hard" return off Yamashiro amidst the transients of the splashes. At 0359, Yamashiro was probably headed roughly 300, Maryland's reciprocal, and presenting her full broadside to Maryland. As Maryland was not yet visually masked, quick confirmation was probably sought from the directors. Broadside on and afire, Yamashiro was probably easily identified and fire was commenced. Maryland probably held a solid radar target for the next three to five minutes and then probably lost the target briefly (0404-0405?) in her turn to 270 as the superstructure masked the Mark 3 radar on the after director and it slewed around to reacquire on a port bearing. With the broad target angle presented by Yamashiro at this time, reacquisition was probably not difficult. Throughout, Maryland's forward director should have been able to remain visually on target.

At sometime around 0402-0403, the cruiser line finally unmasked Pennsylvania. By this time she would have been presented with a beautiful visual and radar target as Yamashiro opened her profile coming to 265. However, Pennsylvania was also in a turn to 270 and her Mark 3 on her after director was probably masked at least until about 0405 at which point it could commence establishing a lock. This gave Pennsylvania four minutes without obstruction to engage Yamashiro.

Meanwhile Mississippi was getting her second chance. Unmasked later than Pennsylvania and at about the time the turn to 270 was complete (~0405-0406), Mississippi's Mark 3 would not be masked (assuming she had both fore and aft installations). This gave Mississippi three minutes without obstruction to engage Yamashiro, at the end of which she successfully got off one salvo.

There were probably several important factors in Maryland's success and the failure of her fellow Mark 3 ships: 1) Maryland enjoyed the most time unmasked. 2) Maryland enjoyed the best geometry to gain a solid radar contact soonest. 3) Maryland enjoyed the best geometry to gain a visual contact soonest. 4) Maryland's radar operators were probably somewhat more proficient. 5) Maryland's gunnery officer was probably somewhat more certain of his target and/or more decisive about engaging it.

Given the Mark 3 FCR's good range discrimination and poor azimuth discrimination, Maryland, Mississippi and Pennsylvania should all have had solid range information on Yamashiro prior to 0353.

Between 0353 and 0355 their radar contact would have suffered some clutter from the transients of West Virginia's shell splashes. During this period, both Maryland and Mississippi should also have had a clear visual to the target as well and should have picked out its rough azimuth, however, they were presented with a very narrow visual target and might have perceived nothing more than the transient visual images of the shell splashes.

Between 0355 and 0359, the Yamashiro was probably badly obscured on radar due to the profusion of shell splashes as a result of the fire from West Virginia, Tennessee and California. By 0359, Yamashiro's turn to port presented a larger radar target that became distinctly "hard" within the "soft" returns of shell splashes, reestablishing the ship's range. At the same time, afire and broadside on, Yamashiro probably became a distinctive visual target, and was therefore discernable in azimuth. At this time, Maryland was the only unmasked Mark 3 ship and she opened fire. Mississippi and Pennsylvania may not have clearly perceived Yamashiro visually past the flashes of the cruiser line's fire.

Apparently, having found the target, Maryland held it and continued to fire as she was masked. Pennsylvania remained masked until ~0405 and Mississippi until ~0406. This presented both Pennsylvania and Mississippi an opportunity in which they would have had solid range information from the Mark 3 and visual azimuth information on the burning Yamashiro to establish a fire control solution. Mississippi accomplished this in three minutes and fired her salvo as Oldendorf ordered "cease fire" for fear he was shooting at a friendly destroyer. Pennsylvania did not.

Why did Mississippi obtain a solution, but not Pennsylvania, particularly given that Pennsylvania had an extra minute? The explanation may be that Pennsylvania's Mark 3, positioned aft, was still partly masked by her superstructure as she completed the turn to 270, while Mississippi, with dual (fore and aft) Mark 3 installations was able to track Yamashiro with her forward Mark 3.

However, from ~0400 until 0409 Yamashiro presented a very broad and strong radar profile to the Mark 3 sets, so at any time during that period, Mississippi should have held a solid target in range. From ~0400-0402, while on course 120 Pennsylvania should also have been able to hold a solid target, and again from 0406-0409. Quite probably the gap was less than four minutes and more like one minute that the Mark 3 aft was completely masked.

So why did Mississippi not open fire at 0406, the moment she was unmasked? And why did Pennsylvania not open fire at the same time, assuming she had to complete her turn to unmask the aft radar? This is where the situation might be one of radar operator and gunnery officer proficiency. It might be that Maryland's operators were slightly more proficient with their equipment, her maintainers groomed it for action better, and/or her gunnery officer was more proficient and/or confident.

An aside, to lay to rest one false explanation that has absurdly (given even a brief glance at a track chart of the engagement) persisted for years: The issue was never one of firing over the cruiser line. West Virginia commenced fire at ~21,300 yards with the cruiser line anywhere from 6,700 to 4,200 yards to the south. Tennessee and California commenced fire at ~20,400 yards with the cruiser line anywhere from 6,200 to 4,000 yards to the south. Maryland commenced fire at ~19,300 yards with the cruiser line anywhere from 6,000 to 4,200 yards to the south. None of these ships had any compunctions about firing over the cruisers of the eastern cruiser line as these ships progressively crossed their line of fire. Thus, the physical positioning of the cruisers did not preclude Mississippi or Pennsylvania from firing over them.

A final aside, explaining the difference between the Mark 8 and Mark 3 FCRs: The Mark 3 FCR had a small pulse width and a broad beam width. As a result it achieved extremely good range discrimination, but poor azimuth resolution. Thus when Washington engaged Kirishima at Second Guadalcanal with such equipment, it was using radar range inputs and visual azimuth inputs to the fire control computer.

The later Mark 8 FCR was a centimetric radar with a more refined wavelength and beam width as well as the small pulse width of the earlier set. This permitted the Mark 8 to establish both range and azimuth very precisely. It also permitted the Mark 8 to generate a much "harder" return off of a much narrower target, and to better discriminate targets in close proximity. By extension, with such refined radiation parameters, the Mark 8 was less likely to have its display cluttered by transient "soft" returns such as shell splashes. This explains the ability of the Mark 8 ships at Surigao to initiate and maintain fire on the Yamashiro regardless of the target angle and visual masking from the cruiser line during the engagement.

Appendix: US Battleship Ammunition at Surigao Strait

Data from "Two Ocean War" by S.E. Morrison.
Ship Capacity Total On-Board AP HC Rounds Expended (all AP)
West Virginia 800 375 200 175 93
Maryland 800 685 240 445 48
California 1200 318 240 78 63
Tennessee 1200 664 396 268 69
Mississippi 1200 744 201 543 12
Pennsylvania 1200 453 360 93 Did not fire

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30 April 2002