This
article isn’t meant to be a full technical description of the
Porpoise and it’s construction. My reason for starting it was a
realisation that whilst the existence of the Porpoise is well known
to most modellers with an interest in D-Day, very little has been
written about how they were actually employed by the units involved.
Whilst researching the role of 27th Armoured Brigade and the Sword Beach landings, I
started to come across references to the use of Porpoises by a number
of regiments and it seemed to me that further investigation would
prove useful.
One of
the many concerns of the Overlord planners was the provision of
sufficient ammunition for the tanks involved in the initial assaults.
Whilst provision had been made for the landing of ammunition lorries
as early as H+15 minutes, there were still worries about the amount
of ammunition available. A novel solution to this problem was
proposed and this became the Porpoise sledge. This was a long,
shallow metal 'box' divided into two compartments, each sealed with a
watertight lid. The towing vehicle was a tank or self-propelled gun.
When fully loaded, the sledge was dragged along the seabed but if
only partially filled, it would float behind the tank. Once on the
beach, the sledge was dragged behind the tank to a collection point.
This provided an instant ammunition reserve for units operating close
to the beaches.
Although
designed to float when partially loaded, it was almost certainly not
used in this role. Trials were carried out using a Valentine DD and
this seems to have been successful. The Valentine DD's single
propeller meant that the towing eyes on the rear of the tank were
available to tow the Porpoise. When it came to the Sherman DD, the
twin propellers were located in such a way that the normal towing
eyes would be masked by the props – making towing by this method
impossible. Instead, new towing lugs were fitted under the lip of the
skirt. However, despite this there is no evidence that Sherman DD
units were actually issued with them. Whilst it was quite feasible
for a wading tank to tow a floating Porpoise ashore, it would make
little sense. Why half-load a Porpoise so that it could float, when
you can fully load it and drag it ashore behind a wading tank? The
maximum 'floating' weight was 1280 lbs – anything more and the
sledge was dragged along the seabed to the shore.
The
Porpoise sledge was produced in two sizes, although it is unlikely
that the narrower version was used operationally. The Porpoise No. 1
Mark 1 was designed to fit between the tracks of smaller tanks such
as the Matilda and Valentine. The Porpoise No. 2 Mark 1 was wider and
would sit comfortably between the tracks of the likes of Churchills,
Shermans and Cromwells. Although it was perfectly feasible for the
Porpoise to be towed by trucks and other vehicles, there was no
practical advantage to this. The whole purpose was to stow the sledge
underneath vehicles on the landing craft to maximise load space - the
wheelbase of most wheeled vehicles was too narrow to permit this.
However, some armoured regiments had other ideas as we shall see
shortly…
The
description and notes below refer exclusively to the wider No.2 Mk 1
Porpoise.
The No.
2 sledge was a pressed steel box, 13' 6'' long, 4' 6'' wide and 1'
deep. It was designed to carry a variety of ammunition, ranging from
rifle calibre ammunition to 105mm howitzer shells - depending on the
vehicle it was intended to support. Two removable hatches in the top
of the sledge allowed access to the ammunition lockers. These lockers
were filled with a series of metal cages – the standard fit being
24 cages. When configured to carry 17 pdr ammunition the normal cages
were replaced with 10 special cages, each carrying three shells. A
series of wooden packing strips to held the cages in place.
The
Porpoise was attached to the towing vehicle via a pair of telescoping
towbars. These could extend from 6' 11'' when fully stowed, to 12'
6'' when fully extended. The vehicle attachment points were fitted
with explosive bolts, so that the sledge could be jettisoned if
necessary. When towed off a landing craft, the maximum recommended
ramp angle was 25 degrees. If the ramp was steeper, there was a
likelihood that the towing bars would become distorted. However, the
official pamphlet points out that this would not necessarily make
them unusable in the short term.
Although
the idea was to load the Porpoise before it was embarked, practical
tests showed that it was much better to tow the sledge aboard empty
and then load it. The primary reason for this was that the sledge
needed to be manhandled into place and an empty sledge was far easier
to move about. Once aboard, the Porpoise was then loaded with the
required ammunition. Each Porpoise was issued with a 15 foot length
of chain, to be used when towing the sledge aboard a landing craft.
The chain was linked to the back of the Porpoise and attached to the
front of the towing tank. The tank reversed onto the landing craft,
dragging the Porpoise into the vehicle well.
There
were two methods recommended - differing only in the number of
vehicles involved. The first option was that each tank would tow a
Porpoise aboard. The Porpoise would be disconnected from the tank,
positioned on the deck by hand, loaded, sealed and then the tank was
backed over it. The second option was to use one tank to tow all the
sledges aboard in turn. In both cases, the ammunition was brought
aboard the landing craft on RASC trucks and stacked in 'loads', each
one placed along the edges of the tank deck adjacent to where each
Porpoise would be located. Although photos of Porpoises being loaded
onto landing craft before D-Day exist, it is unclear whether the
Porpoises are empty. It may be that the loading notes came as a
result of the D-Day experience (the pamphlet initially used as a
reference was published in October 1944).
The
original idea was to stow each Porpoise under it's own towing
vehicle. However, experience soon demonstrated that it took too long
to hitch up the sledge and disembark the tanks. Each vehicle would
have to move forward, wait until its Porpoise had been attached and
then disembark. Instead, the Porpoise was linked to the tank directly
ahead of it. This allowed almost all the sledges to be linked up
before the landings commenced. The rearmost tanks in the landing
craft clearly didn't have this advantage, so their Porpoises were
placed adjacent to the vehicles and were attached to the tanks before
they disembarked.
So
much for the theory - how were they really used?
The
Porpoise was widely used on D-Day, but again, little photographic
evidence remains. Most assault units on the British/Canadian beaches
employed the Porpoise but it is seldom mentioned in any detail in
their own records. The Royal Engineer Assault Regiments towed them
behind Churchill AVREs. The Royal Marine Armoured Support Group
(RMASG) hitched them up to their Centaurs and the armoured assault
brigades (of which the DD regiments were part) used them too. What
seems clear from some records however is that many crews had not
actually towed them prior to D-Day. This suggests that as with many
other types of specialised equipment designed for D-Day, sufficient
quantities were only available at the last minute.
Leaving
nothing to chance, stowage diagrams were issued for each type of
landing craft used for the D-Day landings. The
three types in question were the LCT Mk 3, 4 and 5, It does not
appear that Porpoises were towed by vehicles being carried by larger
craft such as LSTs (Landing Ship Tank)*.
The smallest type, the LCT Mk 3, could carry up to six large armoured
vehicles (tanks or SP guns) and a similar number of Porpoises. If all
six vehicles were towing Porpoises, they were stored underneath the
vehicle immediately behind the towing vehicle. The exception was the
rearmost vehicle, which clearly had no room behind it. In this
situation, the porpoise would be stowed beside the vehicle, ready to
be hitched up as soon as space available for the vehicle to pull
forward as the others disembarked. The larger LCT Mk 4 could carry up
to nine large AFVs with Porpoises. Once again, the sledges for the
rearmost tanks were stowed between the two rows of vehicles rather
than under them. The American-built LCT Mk 5 was different again and
in this case, all the porpoises could be linked up to their towing
vehicles before disembarkation.
*
A
possible exception to this might be A Squadron of the East Riding
Yeomanry. ERY were part of the reserve element for Sword Beach and
were not expected to land before the early afternoon. They were
originally meant to travel across the Channel in LCTs, and indeed for
Exercise Fabius IV on 4-5 May 1944 landed in this fashion. However,
due to a shortage of LCTs (possibly related to the decision to
assign more LCTs to some earlier waves in order to lighten each
craft's load), they were instead loaded into an LST. On arrival off
Sword Beach on the afternoon of 6th June, they transferred
to Rhino Ferries for the last stage of the journey to the French
Coast. The hair-raising description of this transfer from ship to
ferry in the choppy waters off the coast is bad enough, but trying it
with a Porpoise in tow would have been an absolute nightmare. It's
unlikely, but not impossible that Porpoises were embarked with this
Squadron.
In
practice, the number of Porpoises carried in any LCT (if they were
carried at all) seems to have averaged about five. It was therefore
possible to load each LCT in a way that ensured all the Porpoises
were hitched up before disembarkation. On LCT 610 (chalk no. 212),
carrying elements of 13/18 Hussars, three Porpoises were embarked.
Whilst there were six tanks on board, two belonged to the regimental
HQ and one vehicle was the C Squadron ARV. The other three tanks all
belonged to C Squadron and all towed Porpoises ashore including
‘Carole’ (a Sherman Vc Firefly, turret no. 71), subject of the
Dragon 1/35 and 1/72 scale kits.
Another
source of Porpoise information is the landing tables for D-Day. These
comprehensive listings are held at the National Archives in London
and lay out the individual loads carried by each landing craft and
the units to which the vehicles and troops belonged. Whilst they
should not be relied upon in isolation, having been issued originally
on 19th
March 1944 and modified here and there at a late stage, they remain
largely accurate. The tables list the number of Porpoises carried in
each craft. The only 'first tide' listing I have found are those for
3rd
British Infantry Division (Sword Beach). Listings also exist for Juno
and Sword Beaches, but they only cover later landing sequences.
As
mentioned earlier, I came across a number of references to the use of
Porpoises whilst researching the activities of 27th Armoured Brigade
and this prompted me to look into the subject more widely. Further
searching turned up more references to Porpoises as used by other
units, but not in the same degree of detail. The following notes
concentrate on 27th
Armoured Brigade simply because it is the area in which I have
undertaken most research. Other information is also listed where I
have been able to find it.
27th
Armoured Brigade
The
Regimental and Brigade War Diaries, along with personal memoirs from
the regiments, make comments about the employment of Porpoises. A
range of photographs also exist of C Squadron, 13/18 Hussars as they
prepared for the invasion. Many show the Porpoise towing arms stowed
across the front of the tank in addition to the spare track,
roadwheels and return rollers that virtually all tanks within 27th
Armoured Brigade carried. There are also photos of C Squadron loading
their tanks onto landing craft, late on 3rd
June 1944. These demonstrate the approved method of loading the
porpoises. As each tank backed into the LCT, it dragged a Porpoise
backwards using a chain issued for the task.
The
27th
Armoured Brigade Operations Order No. 1 for Operation Overlord lays
down a specific procedure for the employment of Porpoises. The
brigade included three armoured regiments, each operating Sherman
Tanks. 13/18 Hussars would operate two squadrons of Sherman V DD
tanks and one of Sherman III wading tanks (with four Sherman Vc
Fireflies) for the initial assault. The Staffordshire Yeomanry would
operate as a 'wading' regiment and come ashore around three hours
later, whilst the East Riding Yeomanry would also operate wading
tanks and come ashore in the early afternoon. The latter regiments
operated Sherman IIIs, with Sherman Vc Fireflies.
The 15
Porpoises belonging to 13/18 Hussars were towed ashore by tanks from
C Squadron, who landed at around H+45 minutes. Their purpose was to
provide replenishment for the DD tanks that had arrived at H-Hour and
might now be short of ammunition. Once ashore, the porpoises were to
be dumped in an area above the high water mark that had previously
been cleared by flail tanks. Specific instructions were given about
not leaving the porpoises below this level because of the danger they
would pose to other vehicles when they were covered by the rising
tide - particularly 'B' vehicles (trucks and other softskins).
Where
possible, the tanks would return to the drop-off point to re-arm.
Given that this might not prove possible, the Ops Order instructs
each regiment to assign two half-tracks to ammunition re-supply
duties. The crews of the half-tracks would open the porpoises at the
drop-off point and load as much ammunition as possible into the
vehicles. They were also instructed to tow unopened Porpoises to
wherever the tanks were situated, should this prove necessary. Once
the ammunition had distributed, the half-tracks would report to the
Regimental Aid Post (RAP) and come under the command of the Medical
Officer. If required, the half-tracks would report to the RAP
earlier.
The same
procedure was laid down for Staffordshire Yeomanry, landing at around
1040 (H+195) and East Riding Yeomanry who were due to land at around
1330 (H+360). Each regiment had its own drop-off point, normally the
initial rally point and de-waterproofing area.
The
concept of using half-tracks to tow fully loaded Porpoises had been
tested out whilst the Brigade was based in Scotland in March 1944. A
vehicle from 13/18 Hussars was used to try the idea out and whilst
the regimental War Diary makes no mention of the outcome of these
tests, it was clearly considered a success. Within days of the
trials, the method had been incorporated into the planning for the
final landing exercises before Overlord. Although included in the
planning, other accounts indicate that for most tank crews, their
first experience of towing Porpoises was at the beginning of June
1944, as they moved from their camps towards the embarkation points
on the coast. The War Diary of the 13/18 Hussars comments that this
last minute introduction to the Porpoise caused delays on the road
march, as each crew got used to the towing procedure.
Once
ashore, C Squadron 13/18 Hussars found the planned drop-off point for
the Porpoises was unsuitable.
Those
that survived the journey across the beach were towed further inland
to another rally point before being left. Of the 15 Porpoises issued
to 13/18 Hussars, only five survived the trip across the beach. The
other ten were left on the beaches, mostly as a result of being run
over by other tanks and ripped off the backs of the towing vehicles.
The C Squadron Diary relates
that in most cases, it was the towing arms that gave way, leaving the
Porpoise itself stranded in the middle of the beach. Given the
well-documented congestion on the beaches and the delays in clearing
the beach exits, it perhaps surprising that any Porpoises survived
the experience. Of the remaining five sledges, at least one was run
over on the beach but remained attached to its tank, albeit at a
somewhat drunken angle. This belonged to Lt Eric Smith, Troop Leader
of No. 4 Troop. He towed his Porpoise inland, with the sledge
following slightly to one side of the tank. As the tank rounded a
corner, the wayward Porpoise caught three soldiers unawares and
knocked them off their feet. Thankfully no injuries were incurred and
having checked on the state of the soldiers, Lt Smith proceeded on
his way.
Arriving
some three hours later, the Staffordshire Yeomanry also had problems
getting off the beach. The rising tide had reduced the beach to
little more than a thirty foot stretch of sand. They were stuck in a
traffic jam for nearly an hour, before they were able to move off the
beach through their designated exit. Given these delays, Lt-Col
Eadie, their CO, decided to bypass the initial rendezvous point and
move directly inland to a crossroads near Hermanville before
regrouping. Although no detailed reference is made to their use of
Porpoises, their war diary does note that they dumped their porpoises
in this assembly area.
Other
references to Porpoise use.
These
are in no way meant to be a comprehensive listing of Porpoise
references. They are purely those that I have come across in my other
research.
The
Centaurs of 5th
Independent Battery RMASG (Royal Marine Armoured Support Group)
apparently towed two Porpoises. After waiting for some time near the
waterline, the tanks moved up the beach towards the first ‘lateral’
(the first road along the shore, virtually on the beach). Medical
teams on the beach used this as an opportunity to move casualties up
the beach by loading them onto the Porpoises.
76th
Field Regiment (RA) towed Porpoises ashore on Sword Beach behind
their M7 Priests. There is little comment about their use, but Norman
Scarfe in 'Assault Division' (his history of 3rd
Infantry Division in NW Europe), includes a comment that suggests the
Porpoises were considered more trouble than they were worth. As a
young subaltern in 76th
Field Regt at the time, his comments probably come from the heart.
13th
Canadian Field Artillery, landing M7 Priests on Juno Beach, had other
concerns. The friction caused by prolonged towing of the sledges,
particularly over hard-surfaced roads, caused a build-up of heat in
the ammunition compartments. There were fears that this heat build-up
could cause an explosion. Extended towing over hard surfaces also led
to a rapid deterioration in the bottom plate of the sledge. By the
time the regiment's Porpoises had reached the drop-off point some way
inland from the beach, several of them were worn through on the
undersides.
86 Field
Regt RA (Hertfordshire Yeomanry), the only regiment to land Sexton SP
Guns on D-Day (Juno Beach), found that their Porpoises caused less
trouble than expected. The C Troop diary records:
"The
Porpoises - those misbegotten children of the "War House"
proved to be quite amenable to a wet landing and all were landed
without any trouble. Perhaps this was as a result of the language
used on them previously....".
The
first Troops ashore were A, C and E Troops, landing at around H+60,
or roughly 30 minutes ahead of schedule. B, D and F Troops landed at
around 1000. The vehicles were delayed on the beaches before moving
inland. Their diary records that they reached the Mont Fleury Battery
and dumped their Porpoises at this point. However, there is also
evidence that some of the more enterprising gun sergeants used the
delay in getting off the beaches to unload the Porpoises and cram the
spare ammunition into any available nooks and crannies in the
vehicles, rather than tow them any further inland. This may account
for the presence of some abandoned and apparently empty Porpoises in
one or two photographs of the Juno beach areas.
The
Sherbrooke Fusiliers, landing on Nan White Beach (Juno) at around
1215, record that their Porpoises were used as impromptu infantry
transports, carrying infantry of the North Nova Scotia Highlanders to
the main assembly area codenamed 'Elder'.
Long delays due to congestion on the roads meant that they didn't
reach Elder until around 1800.
My thanks to Neil
Wharton, Nick Perry, the Tank Museum Library and the National
Archives in London for information, assistance and ideas in equal
measure.
Porpoise
Ammunition Loads
(Ammunition was loaded
into 24 baskets within the Porpoise – except for 17 pdr
ammunition). The steel baskets were of a standard size, so in theory,
each Porpoise could carry a mixed load of ammunition (in particular a
mix of 75mm and machine gun ammunition for the tanks). However, the
implication of various records would suggest that only one type of
ammunition was carried in each Porpoise – with the ammunition type
being indicated on loading stencils on the upper deck of the sledge.
| Calibre | Per Basket | Floating* | Full Load |
| 7.92mm Besa | 4 boxes | 54 boxes | 96 boxes |
| .30 cal | 4 boxes | 64 boxes | 96 boxes |
| .50 cal | 2 boxes | 44 boxes | 96 boxes |
| 6 pdr | 4 rounds | 70 rounds | 96 rounds |
| 75mm | 4 rounds | 50 rounds | 96 rounds |
| 25 pdr | 2 rounds | ?? | ?? |
| 95mm** | ?? | 38 rounds | 48 rounds |
| 105mm** | ?? | ?? | ?? |
| 17 pdr# | 3 rounds | ?? | 30 rounds |
*The maximum load for
floating Porpoises could not exceed 1280 lbs, so the basket loads
were reduced accordingly.
** Contemporary records
indicate that this ammunition type was carried in Porpoises, but no
official stowage details have been found.
# 17 Pdr ammunition was
significantly larger than other types and was carried in ten
specially constructed cages in the Porpoise
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