* Particular thanks to Duncan Munro who provided this copy of HMS Illustrious' Gunnery Report for the Operation Excess action.



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DATE …. 7th February, 1941. No.3363/0197


          (Copies to :- Vice Admiral, Light Forces
                                Rear-Admiral, First Battle Squadron
                                Rear-Admiral, Third Cruiser Squadron
                                The Captain, H.M.S. “Excellent”

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The following report contains the lessons learnt and recommendations put forward as a result of various actions in which “Illustrious” was engaged with German and Italian aircraft during the period January 10th – 19th, 1941.

The report is divided up as follows :-


(A)   Lessons Learnt

(B)   Recommendations.


(A)   Damage to Gunnery Material.

(B)   Recommendations for Modifications to Equipment


(A)   Lessons Learnt.

(B)   Recommendations.


(Page 1 of “Illustrious” Report No.3363/0197 date 7th February 1941)


(A)   Lessons Learnt.

1.       The most important lessons learnt in the various actions in which “Illustrious” was engaged by massed formations of German Dive Bombers over a period of 10 days was that affecting personnel.

2.       During this period, in which attack was likely at any time during daylight hours, officers and men were subjected a severe physical and mental strain in which the latter, in particular, became so acute that by January 19th the majority of the ship’s company had come to the limit of its nervous endurance.
It therefore became increasingly necessary to stiffen Pom-Pom crews by the inclusion of more and more officers so that during the last attack on Sunday 19th January the five serviceable Pom-Poms were each being fought by crews of three made up as follows :-
5 Officers
5 Petty Officers
1 Leading Seaman
4 Able Seamen
In addition to the above five officers, one Fire Distribution Officer was stationed at each Pom-Pom mounting as was the normal practice in “Illustrious”.

3.       While it is unlikely that such a state of affairs will often be encountered, the violence of th effect on such a large number of men, whose previous morale was extremely high, forces one to certain definite conclusions.


4.       (a) While fear is instinctive its mastery depends almost entirely on the character of the individual. In this connection it was most marked that men of normally bad character, but who were considered tough, failed to stand the strain whereas quiet and steady characters reacted well.

(b)   The effect of a prolonged expenditure of nervous energy can never be apparent in training and it was interesting to observe for it caused a reduction of efficiency and quickness of thought akin in appearance to the sight of a rabbit with a weasel.

(c)    During the first day on which “Illustrious” was attacked 6 times these signs began to be visible and the cumulative affect became increasingly evident with the ship lying alongside as the centre of attraction for repeated dive bombing attacks.


(B)   Recommendations.

5.       The selection of Higher Gunnery A.A. Ratings should depend to a greater extent on strength of character than on technical or educational attainments. The nautral tendency to judge a man’s action efficiency on what he does when training is most misleading: in fact, the efficiency of the average seamen of 20-21 falls off very considerably as soon as his ship starts to take punishment.

6.       In view of para. 5 every possible step should be taken to substitute Power-follow-up for Human links. The former is neither subject to feeling nor does it need training; so long as it is maintained efficiently, is designed to stand up to shock and is reasonably protected against splinters it will work more consistently, accurately and with less lag than the average Seaman under action conditions, who should, however, be retained as a human link in case power-follow-up breaks down.


Page 2 of “Illustrious” Report No.3363/0197 date 7th February 1941


(A)   Damage to Gunnery Material.


7.       4.5-inch Mountings
Elevating Worm of Y.2 mounting damaged by a bomb splinter which came through the After Lift well, Y.2 Gun Bay’s bulkhead, and a 4.5in R.U. Locker.

8.       Roof of Y.1 and Y.2 Mountings pierced by bomb splinters from the same bomb.

4.5-inch Ammunition Conveyors

9.       A direct hit just above the Hangar deck at 130 station wrecked the After Conveyor.

10.   A direct hit in the After Lift Well at 158 station wrecked all 4 delivery ends of the After Conveyor.

4.5-inch Endless Chain Hoists

11.   Distortion of the Upper Deck by explosion and blast jammed all upper chain hoists except those in”A” Group. Those in “B” group were made serviceable 4 days later. The remainder are still jammed.

Pom-Pom Mountings

12.   A direct hit annihilated S.2 pom-pom.

13.   A bomb splinter from a near miss pierced the Upper Gallery deck and struck the live roller ring of P.2 pom-pom thus temporarily jamming the mounting in training.

14.   A bomb struck the right rear upper feed rail of P.1 pom-pom a glancing blow, bent the guard rails around the mounting and the trainer’s platform in such a way that the mounting was temporarily jammed in training.

15.   S.2 pom-pom was temporarily jammed in training and elevation by the jib of the Flight Deck Travelling crane which was blown on to the gun by the explosion at S.2.

4.5-inch Directors

16.   The left end reflectors of the U.D.4 heightfinder in ‘B’ director were smashed by bomb splinters or bullets.

17.   The drive from the Gyro Roll Unit motor in ‘A’ director became disconnected twice, due to the shock of a near miss; this released one side of the differential to Director Setting which latter then ran free without elevating the director sight.

Gyro Roll Correctors Mk.VIII

18.   A near miss broke the gimbals of the gyro roll correctors in ‘A’ and ‘B’ T.S. and parted the flexible drives of director training from the H.A. Tables to both roll correctors.

Electric Circuits.

19.   All circuits between ‘X’ and ‘Y’ directors and groups of guns were cut by the first direct hit in the after lift well and by bomb splinters in leads from both directors to T.S.s.

20.   All circuits to B.1 were cut by the explosion at S.2.

21.   The whole evershed system was put out of action by damage to circuits to ‘X’ and ‘Y’ directors.


Page 3 of “Illustrious” Report No.3363/0197 date 7th February 1941


4.5-inch Twin S.D. Mountings.

22.   The continual banging of the 4.5” Loading Tray on the Breech ring stop has been found to close in the rammer slides at the breech end of the tray, thus causing the rammer to jam; this needs rectification.

23.   It is considered that smoother and quicker loading would result if the rammer lever were modified so that it can be worked by No.2 and not No.3. The former has nothing to do except close the interceptor when the gun is in S.A.

24.   The arrangement of the revolving ammunition stand is not liked for the following reasons :-

a.       The spring loaded handle for locking the stand is difficult to work with the foot, which experience shows that supply numbers use.

b.      Time is wasted by supply numbers in fitting the base of the cartridge into the pocket.

c.       In barrage fire use of the stand cuts down the rate of fire very appreciably for the reasons stated in (a) and (b).

d.      The position of the stand is such that it is difficult to ram the nose of the projectile really firmly into the fuse-setting machine; failure to do this makes for bad fuse-setting.

25.   In the meantime it has been found essential to have one man detailed permanently to work the tray locking handle (pedal) in H.A. firing. This is done at the left gun by the sightsetter but an extra man should be allowed in the Quarter Bill for the right revolving tray.

26.   The leather covered cartridge stop at the rear of the 4.5-inch loading tray is insufficiently robust and after some time bends backwards, thus failing to steady the base of the cartridge.

27.   At extreme elevations it is very difficult for numbers 3 and 4 to push over the tray. It is for consideration that gear should be designed in which the recoil of the gun cocks a spring which automatically puts over the tray after the gun has run out. An interlock would be required to prevent an unloaded tray being moved.

28.   The provision of blast warning gear is unnecessary. In no action has blast ever been noticed by Director or pom-pom’s crews and, even if it were, crews would evacuate their quarters without reference to blast warning lights.
In addition they are a menace at night when, without warning, they suddenly light up and may jeopardise the safety of the ship.

29.   The brass stop which limits the movement of the tripper lever when the air blast is tripped should be much stronger and made of steel. Bending of this stop caused air blast to jam at two guns.

30.   Despite these minor difficulties the consistent working of the 4.5-inch guns and mountings at which, in the aggregate, eight guns fired approximately 3,000 rounds of H.E. at an average rate of fire of 12 r.p.m. in an aggregate time of about 30 minutes, was remarkable.


Page 4 of “Illustrious” Report No.3363/0197 date 7th February 1941

4.55-inch Turret Pumps

31.   These have never given a moment’s trouble but the following proposals for their general improvement are put forward :-

a.       Each pump in any one group should run on a different H.P. Electric supplies.

b.      With this arrangement, and when pumps are cross-connected, oil pressure will be assured in both turrets at all times until both electric supplies are cut.

c.       It is believed that oil-cooling is being fitted in New Construction ships. The need for this is confirmed.

4.5-inch Gun Bays

32.   The general layout proved excellent with the following exceptions :-

a.       It is considered that the decks and bulkheads surrounding 4.5-inch gun bays and turret pump spaces should be made of splinter proof steel. A good deal of damage and casualties in ‘Y’ group would not have occurred if this protection had been provided.

b.      When guns are fired across the Flight Deck, as they frequently are, space in rear of the mountings, i.e., on the outboard side of the gun bays, is very cramped: the difficulty of providing more space is, however, fully realised.

c.       The desirability of R.U. bottle-rack instead of locker stowage is amply confirmed.

d.      Vertical R.U. Ammunition racks are definitely required on the outboard side of the gun bays. 10 have been fitted in each gun bay in ‘Illustrious’ but twice this number is required.

e.      The need for turret pump starters and by-pass valves being operable from the gun bays is continually felt.

4.5-inch Ammunition Conveyors

33.   These work most satisfactory, with the following exceptions :-

a.       The method of lubricating inside the gear box is unsatisfactory and causes the end thrust roller-race to seize up.

34.   Heavy damage to the after conveyor at 130 station and a direct hit between 155 and 161 stations made it impossible to clear all the ammunition, this being trapped for some days. This was unfortunate, since a fire was burning beside the conveyor for several hours. To overcome the recurrence of this danger the following modifications in design are required :-

a.        It should be possible, by removal of inspection covers, to remove rounds from any part of any jammed track.

b.      It should be possible to remove any section of cover plate by unbolting it from adjacent sections and the bed-plate. This is not possible because the guide-ways in which the wto outer upper and lower tracks run are welded to the cover plates; since it


Page 5 of “Illustrious” Report No.3363/0197 date 7th February 1941

4.5-inch Ammunition Coveyors. Contd.

                                Is also impossible to remove sections of track everything is securely locked.

c.       The existing arrangement of mechanical interlocking gear between the watertight doors, hand-power clutches and conveyor motors, at the delivery ends of conveyors is unsatisfactory. At the best of times the interlocks need careful adjustment: if the gear is distorted by shock or splinters an otherwise serviceable track may be stopped.
It is considered that the W/T doors and hand-power clutch should positively operate electric switches placed in the conveyor motor’s starting circuit..

d.      The run of Teleflex Gear along the side of conveyors should not be attached to the cover plates but along the side of the bed plates.

e.      The Teleflex Gear as fitted in “Illustrious” conveyors is most unsatisfactory. In many cases it is impossible to move at all while in the remainder the pointers have a knack of settling half-way between two adjacent orders. Teleflex order instruments should work indicating lights in each sector of the existing dials at one positions.

f.        Steadying belts are unnecessary and have never been used.

4.5-inch Endless Chain Hoists.

35.   These work consistently well and need little upkeep. Action damage to the ship showed, however, that the following modification is required :-

a.       The elongated slot which allows for adjustment caused by stretch of the chains must allow for stretch in BOTH directions, incase the whole outer tube in which the hoist runs is itself stretched. This occurred in 6 out of 8 upper hoists when the upper deck, to which the bases of the hoists are secured, buckled downwards.

b.      The existing design of auto-lock seriously delays the clearing of jammed hoists. A simply operated pawl and ratchet arrangement is required, to enable hoists to be reversed.

Secondary Supply of 4.5-inch Ammunition.

36.   Experience proved conclusively that the most speedy and flexible method of secondary supply is by human chain, and in no instance would hand-working of hoists or conveyors have been either desirable or, as it turned out, possible.
It is considered that the provision of hand working for hoists and conveyors might well be done away with.

4.5-inch Directors.

37.   In general these work satisfactorily, but the following recommendations for their improvement are put forward :-

a.       All open sights should be greatly strengthened. They are always breaking or bending.

b.      The H.A.D.F.A.S. is of no use when engaging dive bombers; Control Officers are all agreed that when engaging aircraft in barrage fire they look straight at them and use their DV and DL handwheels to hosepipe


Page 6 of “Illustrious” Report No.3363/0197 date 7th February 1941

4.5-inch Directors. Contd.

                Bursts on to the target. This may or may not be sound in theory but it is what happens, and, it is considered, always will happen when engaging large numbers of Dive Bombers.

c.       There is thus a definite need for a C.O.F.A.S. the movement of which in elevation and training drives directly into Director Settings and Training when the Barrage Switch is put to “ON”. Delays in following by No. 4 on the Deflection Screen are unacceptable.

d.      The shock of near misses cause the cotter pin in the drive from the Roll Motor in “A” Director to become disconnected on three occasions. The freeing of one side of the Director Setting differential thus rendered the movement of the Director Setting handwheel useless. This should be rectified.

e.      Target Speed Spotting handle should be worked by the Control Officer

f.        Barrage Switch should be worked by the Control Officer.

g.       Fall of Shot Selector Switch should be worked by Control Officer.

h.      Place Gun ready lamps on layer’s side.

i.         A Clinometer plane on each Director is needed. On two occasions “Y” Director has been badly damaged by aircraft and there has been no positive datum on which to work when replacing damaged parts of the sight.

Pom-Pom Directors.


a.       In order successfully to engage massed dive bombing attacks, when no aircraft can be kept under fire for more than an approximately 5 seconds, the director system must entirely fulfil two requirements :-

                                                                           i.      The sight must be controlled by one man

                                                                         ii.      The gun must immediately and automatically follow up the movement of the sight.

b.      When steaming at the normal speed of the fleet the vibration of the Pom-Pom Directors is great and makes the operation of the Directors most difficult. The vibration is such that the whole C.O.F.A.S. of S.1 Director, on one occasion, snapped off.

39.   While the Mk. III Pom-Pom Director can be used with comparative ease as a one man sight the absence of Power follow up with the resultant time lags and errors in pointer following are considered to render the director useless under action conditions against massed D/B attack. The fact that gunlayers, trainers and No.1’s of pom-poms are almost  certain to look at the aircraft and not at their pointers and fire lights further aggravates the matter.

Pom-Pom Guns.


a.       The functioning of 40 Mk. VIII A.H. V. guns, which between them fired approximately 30,000 rounds, was quite remarkable and in no case did any gun have a major stoppage. By extreme fortune, however, the crank journals of tall guns had just before been modified and dressed up. Inspection since has shown that scoring is again taking place in a large number of guns and it is of the utmost importance that this cause of major stoppages is dealt with quickly.

b.      In nearly every action each mounting fired a full load, i.e. 154


Page 7 of “Illustrious” Report No.3363/0197 date 7th February 1941

                … rounds per gun in continuous fire. While the existing arrangements for filling water jackets is comparatively satisfactory it is not quick enough. Water filling pipes should be fitted with a pistol type filling nozzle like that used on aircraft petrol filling pipes.

c.       The need for flame guards and reduction of flash and smoke is confirmed.

d.      A few stoppages occurred when firing at extreme elevations due to empty cartridges jamming as they left the ejector tube. This matter should be gone into again in order to reduce this cause of jams even further.

Pom-Pom Mountings.

41.   These worked satisfactorily but require modifying in several respects : -

a.       They MUST be fitted with one-man control of elevation and training so that the advantages of the one-man sight may be retained in quarters firing.

b.      Roller paths and live roller wings must be protected against splinters.

c.       Splinter proof decking is desirable under Pom-Poms to protect the mounting and personnel against splinters from near misses.

d.      Stanchions round Pom-Pom mountings should be quickly detachable from and not screwed to the mountings.

e.      In one action a very near missed caused the ship to take a heavy list. This resulted in empty cartridges and links sliding under the mounting and jamming it in training. Skirts should be fitted to ensure that empties cannot become jammed between fixed and revolving structure.

f.        The Safety Depression Control Gear, as fitted in ILLUSTRIOUS is completely useless. It warps and bends to such an extent that every gun in the ship can hit ship’s structure at one or more points, despite the fact that steps are continually taken to build up the push-rod which is the only quick method of ensuring safety. This has had the effect of rendering every mounting useless against low flying T/B aircraft over large arcs of training.

g.       Hand training and elevating efforts are very high due to the unbalanced stated of the mounting.

h.      The cutting of the primary H.P. electric supply to 2’ mountings by bomb splinters put them out of action while changing over to hand, by which time the attack was completed. The change over from No.1 to No.2 supply should work automatically so that the pump will run until both supplies are cut.

i.         Some form of very simple relative bearing indicator is required at each short range weapon wired to the R.D/F Mast Training Magslip gear.

j.        Blast warning lamps are redundant. If blast becomes excessive the crew will take shelter without reference to the lamps.


Page 8 of “Illustrious” Report No.3363/0197 date 7th February 1941

Pom-Pom Crews.

42.   The following lessons were learnt :-

a.       It is not practicable to re-load feed rails while the mounting is in action.

b.      To interrupt guns when the ship is being attacked is unreasonable. No man will allow an attempt on his life while he has a loaded gun.

c.       It is not possible to clear stoppages while the mounting is in action, neither during lulls are they in fact cleared by No.2 or 3. This work is done by O.As. and Q.Os. and any A.A. 1 or A.A.2 who may be at the gun as layer or trainers as is the case in ILLUSTRIOUS.
It is strongly recommended that the Pom-Pom’s crew should consist of only No.2, 4 and 5 who are more than sufficient to bring the guns to the ready and start the pump. No.2 and 3 are redundant before, during and after opening fire.
Nos. 6-11 should be retained for ammunition supply but should ALWAYS take shelter. Events proved that 13 men were killed at Pom-Poms who in fact were serving no useful purpose on their mounting.

Pom-Pom R.U. Ammunition Supply.

43.   The method of stowing R.U. Pom-Pom Lockers is poor. The natural way to lift and carry a belt is to hold the end around each side of the link. R.U. lockers should be made so that belts hang down from rails exactly similar to those of feed rails on the mounting. This would greatly increase the speed with which belts could be removed from lockers and would ensure the quick, neat and therefore economical stowage of R.U. Lockers in action when the latter are being replenished as quickly as possible.

44.   When the immediate R.U. Supply is from a R.U. Pom-Pom Magazine it should be stowed in bulk, hanging from rails similar to feed rails. The speed of re-loading P.1 and P.2 Mountings from their R.U. magazines was very seriously slowed down at a critical moment by having to pull out boxes from the magazine one at a time.

A.D.P/Pom-Pom Communications

45.    The number of close range weapons to be controlled is too large for the A.D.O. to do himself at it has been proved conclusively that a Fire Distribution Officer at each weapon is essential and that they and not the A.D.O. must distribute the fire. The sector lamps therefore become redundant as have in fact never been used. Instead each weapon has its sector of special responsibility. It is possible that, in ships with only one Pom-Pom each side, the sector lamp might be found useful. The only Action communications required are therefore the Mast Alarm cum Check Fire Bell and Lights circuits which ave been found invaluable, particularly at night. Telephones are necessary for reports and policy orders.


Page 9 of “Illustrious” Report No.3363/0197 date 7th February 1941

Evershed System

46.   An efficient target indication system of 4.5” directors is an essential requirement if time lags are to be avoided. The system of Eversheds provided had always worked satisfactory provided it received continual attention.
Without this, it quickly goes out of adjustment. Under Action conditions the Evershed system failed completely. Damage aft and the shock of near-misses caused “Stuck Position” errors large enough to upset the adjustment to such an extent that it was found better to pass bearings  and elevations from the A.D.P. to Director by telephone. The A.D.O. had no immediate means of telling which section was damaged and could not therefore switch off damaged section.
The fitting of Magslip transmission for target indicating circuits is essential.

Splinter Proof Protection.

47.    The efficacy of Splinter Proof Plating was amply proved. Its more general fitting would certainly have reduced damage to material and personnel and it is strongly recommended that further protection should be afforded to the following :-

a.       Round Roller Paths and Live Roller Rings of all Pom-Pom Mountings.

b.      On all decks and bulkheads surrounding 4.5” gunbays and turret pump compartments.

c.       Round all essentials runs of Fire Control circuits. This is particularly necessary in ships with B.D. mountings where guns cannot be controlled locally in Barrage Fire.

d.      Round 4.5” Conveyors.

e.      Round the outer sides of wing bridges.


A.      Lessons Learnt.

48.   The greater the stress under which a man is working the more is he governed by his instinct and a desire to do the most natural and simple thing. This fact showed itself universally in ILLUSTRIOUS in the following ways :-

                                                                           i.      Everybody in a position to do so, was unable to avoid looking at the dive-bombers, and, because it was easier to look straight at them than through a sight only by a most conscious effort could one force oneself to adopt the latter course.
A man does NOT look for the bead of his foresight when shooting a snipe because, at the moment, the bird is of such absorbing interest; large numbers of diving aircraft are at least as fascinating.

                                                                         ii.      A man defending himself with a pistol does not ask for or pay attention to advice on how he should aim his gun when an attempt is being made on his life. He points it at his assailant and fires as and when HE thinks fit. In the same way layers, trainers and No.1s of Pom-Poms each tended to trust themselves when they SAW diving aircraft attacking the ship .lIf they are to be expected to follow pointers and obey fire lights they must be UNABLE to see the aircraft.

Page 9 of “Illustrious” Report No.3363/0197 date 7th February 1941

49.   The above possibilities had been foreseen. For this reason, because of vibration of directors, the lack of power follow-up and because the majority of informed opinion and past experience was believed to show that time lags and pointer following errors were unacceptable, it has been the policy in ILLUSTRIOUS not to use Pom-Pom Directors against Dive-bombing attack.
Nothing that occurred in any of this series of actions did anything but confirm the rightness of this decision.

50.   For the same reasons as explained in 48 (i) the 4.5” Control officers did not use their H.A.D.F.A.S. but looked straight at the target and tried to direct their bursts on to it by applying arbitrary corrections to Dv and Dl.

51.   Had tracer been fired from 4.5” or Pom-Pom guns it is certain that hose-pipe shooting would have been used because in the existing circumstances it would have been the most natural thing to do and one calling for the least mental effort.

52.   With a few seconds only at his disposal it is more than enough to expect a man to aim accurately AT one target; to teach him NOT to aim at it by an amount which depends on factors which he has to estimate and which are constantly altering seems unsound.

53.   The moral and psychological effect of self-destroying ammunition on the pilots of the attacking aircraft was very considerable. The fact that each successive attack was delivered from a rapidly increasing height, with consequent falling off of accuracy in bombing, is attributed to the dislike that pilots had for diving through the crust of bursting shell and smoke puffs the age of which they were unaware.

54.   Had there been a cone and not a crust of smoke burst and head each pilot been able to see the large quantities of projectiles coming his way it seems certain that the psychological effect would have been enhanced. It is in this direction that it is felt that much can be done in a short time to combat massed Dive Bombing Attacks.


55.   Every effort should be made to expedite the production of the one-man local sight and of power follow-up to the existing one-man Director Sight.

56.   As an interim measure the boxing in of Pom-Pom layers and trainers so that they are forced to follow their pointers, might increase the effectiveness of Pom-Pom fire.

57.   The early supply of bright tracer Pom-Pom ammunition will largely meet the requirements of paragraph 53 and will lend to increase the accuracy of fire.

58.   It is considered that all Long Range H.A. ammunition should be fitted 100% tracer. This would greatly assist the Control Officers to hose-pipe in Barrage Fire and will not, it is considered, adversely affect the control of Long Range ??? Controlled Fire.