The South African
Military History Society
Die Suid-Afrikaanse Krygshistoriese Vereniging
Military History Journal
Vol 2 No 6 - December 1973
Field Artillery of the British Army 1860-1960
Part III, 1914—1960
Major Darrell D. Hall
Parts 1 and II, 1860-1914, were published in Vol 2, Numbers 4 and 5.
This period deals primarily with the field guns of the two
World Wars, the 18 pr and the 25 pr. After the frequent
changes of earlier years, these were guns which remained in
service for about 30 years each.
The steps leading to the adoption of the 18 pr have
already been described. The 18 pr was the British Army’s
field gun when the war started in 1914. At that time it was
thought that this would be a war of movement and that the
13 pr, 18 pr and 4.5in howitzer would adequately cater for
the needs of the army in the field. Of course, heavier guns
were also available.
When trench warfare developed and it became apparent
that it would be a static war, more and more emphasis was
placed on heavier calibres and heavier shell weight. Many
heavy guns came into service, but the 18 pr was the gun
which was produced in greater numbers than any other.
Consequently more 18 pr shells were fired than any other
calibre. For example, although 22,400,000 shells were fired
by the 6in 26 cwt BL howitzer, more than 100 million 18 pr
shells were fired.
At first only shrapnel and star shells were available, but
a request was soon made for a high explosive shell. This
shell came into use in 1915.
Both the 18 pr Mk I and Mk II carriages had pole trails.
These limited elevation to 16°, and so range was limited to
6525 yds. Towards the end of the war a Mk III carriage
appeared with a box trail. This allowed elevation to 30°
and range was increased to 9300 yds. It was followed
quickly by a Mk IV carriage with elevation to 37° and a
range of 10,800 yds. The gun (as opposed to carriage) was
also improved, and the Mk IV gun appeared on both the
Mk III and IV carriages, with an improved breech
There were other carriage modifications as well, notably
to the recoil system. The buffer and recuperator were
mounted under the piece. The cradle was lengthened to
provide better support for the gun during recoil, and this
recoil was variable depending on the elevation. This meant
that at maximum elevation the gun could be fired without
any chance of the breech hitting the ground on recoil.
Very few Mk IVs saw service during the war, but this
was the version which was in use between the wars until it
was replaced by a Mk V carriage. This had a split trail
which allowed a 500 traverse. This was very useful for
anti-tank shooting, but it was slow in and out of action, and it
was difficult to handle. Consequently, when a circular platform
was produced for the Mk IV carriage, the Mk V was
dropped. This circular platform was carried under the
Mk IV trail. It provided a simple method of achieving
quick and extensive traverse.
During the ‘20s and ‘30s plans were made for the
modernising of the British Army’s field artillery. It was
decided to replace the 13 pr, 18 pr and 4.5in howitzer with
one all-purpose gun which would fire one shell with variable
charges, enabling it to cover the roles of the three World
War I equipments. it was also decided to dispense with
shrapnel as the improved fragmentation of the HE shell
made the retention of shrapnel unnecessary.
By 1930 the basic design of the new gun had been
accepted. It was to have a calibre of 3.45in and it would
fire a 25 lb shell. This calibre was a compromise, dictated to
a large extent by economy. There were many 18 pr pieces
still in existence, and they could be re-bored to the new
calibre pending the introduction of the completely new
equipment. Also, as the 18 pr Mk IV carriage could accept
the greater recoil stresses of the heavier shell, it could be
used until the arrival of the carriage designed for the new
This interim version was known as the Ordnance 3.45in
but it was referred to generally as the 18/25 pr. The official
title was soon changed to 25 pr Mk I. Sufficient of these
were made available to equip the army.
Much thought was given to the design of the carriage for
the new gun. A split trail was considered; and abandoned.
Finally the designers agreed on a box trail which had been
planned for a 105mm howitzer, which was the equipment
which the designers would have preferred but which, as
explained, economy did not allow.
This box trail was splay-sided to allow for maximum
traverse 80 in all. Secondly it was hump-backed, to
allow a 360 degree firing platform to be carried underneath it.
This was similar to the platform produced for the 18 pr
Mk IV carriage and was like a large wagon wheel. On
coming into action, the gun wheels were pulled upon it.
One man could then lift the trail by the handspike and, if
required, move the gun through a complete circle.
The new equipment was designated the 25 pr Mk II. It
was not produced in quantity until February 1940, and it
first saw action in Norway in April 1940. The British
Expeditionary Force in France had the earlier 18/25 pr,
and most of these were lost in that campaign. The gun with
which most British and Empire field artillery units fought
the war from then on, was the 25 pr Mk II.
The 25 pr had a detachment of six. It was towed into
action by a vehicle which, because of its shape, was known
as a ‘quad’. It looked as if it was armoured, but it was not.
The quad towed the gun and a ‘trailer artillery’ or limber
which carried 32 rounds.
Many types of ammunition were produced HE,
armour piercing (AP) shot, star, incendiary, smoke, flare
and, should it be necessary, chemical. There were four
charges, 1, 2, 3 and super. Maximum range with super
charge was 13,400 yds. The 18/25 pr on the 18 pr Mk IV
carriage was not robust enough to deal with this charge,
so its maximum range was limited to 11,800 yds.
Only limited numbers of super charge were carried for
each gun, as this charge caused excessive wear. This meant
that effective range was considered to be something less than
11,800 yds, the maximum range with charge 3.
Armour piercing shot was produced at the time of the
North African campaign. For this, an incremental charge
was provided which gave the greater muzzle velocity
required to propel the shot faster and further. As it made
the gun unstable, a muzzle brake was fitted. The 25 pr
achieved some success as a tank killer in the Western Desert.
25 prs used by the Australians and New Zealanders in the
Far East did not have to contend with tanks to the same
extent, and so their 25 prs were not fitted with the muzzle
The 25 pr weighed nearly two tons, and this weight
presented problems for some units. It was too heavy for
airborne units and so they were equipped with the American
75mm howitzer Ml. This remained the gun of British
airborne forces until 1955.
For the jungles of the Far East the Australians produced a
‘baby 25 pr’. This had no shield, a cut-down barrel with
flash hider and a shortened trail with a castor wheel for easy
manoeuvring. As the shortened barrel interfered with the
ballistics, range was limited to 10,800 yds.
The Indian Army also modified the gun. Their version
had a short axle but retained the original barrel, for the sake
of the additional range.
The Canadians then produced a hinged trail. This was
combined with the Indian short axle, and the result was the
Mk III carriage.
Various self-propelled (SP) versions of the 25 pr were
produced, but the most successful was the Sexton on a
Canadian Ram chassis. This was the main field artillery
SP gun of British armoured divisions in the last years of
The 25 pr will be remembered with affection by thousands
of war-time gunners and by the troops they supported.
Reliable and accurate, this was a Rolls-Royce among guns.
It remained in service for many years after the war and, in
the South African Army, it is still in use. It was used in
Korea and Malaya, and in other trouble spots which
required British action in the late ‘40s and in the ‘50s.
The post-war years saw the armies of the world preparing
for nuclear warfare, and the Communist threat saw the
establishment of NATO. It was considered that the nuclear
battlefield would see a war of movement with infantry moving
in armoured personnel carriers. Such conditions would require
all artillery to be self-propelled with complete overhead
protection against nuclear fall-out. In addition, NATO
membership required a standardisation of ammunition. In
the case of field artillery the calibre adopted was 105mm.
Apart from its calibre (88mm or 3,45in) being unacceptable,
the 25 pr’s shell was also considered to be too light and its
range too short. Work therefore proceeded on the design
of a new self-propelled gun with a l05mm calibre for the
British Army of the Rhine (BAOR). This gun, known as
Abbot, appeared in the ‘60s and is still in use.
However, the first demand for a change came from the
airborne gunners who, in 1955, had received the 25 pr in
place of the American 75mm, as the 25 pr could now be
parachuted with a suitable towing vehicle. In spite of this
capability, when British airborne troops next parachuted
into action at Suez in 1956, the guns were not dropped with
them, but arrived later by landing craft. This was because of
difficulties experienced by the RAF with the transport
aircraft concerned. This was obviously not acceptable, and soon
afterwards airborne gunners received the 4,2in mortar
which could easily be parachuted from more than one type
of aircraft. In 1957 the 75mm came back for a few years
for use in Aden.
The 4,2 in mortar was originally produced in World War
II to fire chemical bombs. It was later adopted as an
infantry support weapon and HE bombs were developed.
After the war it was handed over to the Royal Artillery. It
was used by gunners in Korea, but it was never completely
accepted as a gunner weapon. Its range was short — just
over 4,000 yds and bomb weight was only 20 lbs, although
its lethal effect was considerable. A mortar bomb does not
have to cope with the stresses of a rifled barrel, and so its
casing can be thinner and explosive content correspondingly
greater. Measures were taken therefore to replace the mortar
as soon as possible with a NATO-approved 105mm gun.
The pattern at this stage was for BAOR regiments to
receive the Abbot SP 105mm, and for so-called strategic
reserve regiments to be equipped with this new 105mm.
Strategic reserve regiments were those in the Parachute and
Commando Brigades and certain other nominated regiments,
all of which were ready for rapid despatch to any part of
The equipment selected for these regiments was an
Italian 105mm pack howitzer. It was a good gun but its
range was only 10,800 yds. It was easily air-portable and
helicopter-borne and was parachutable. Shell weight was
33 lbs and there was a wide range of shell types. The gun
could be stripped down to mule or man loads very quickly.
This was an essential characteristic when manhandling was
necessary in the Borneo jungle during the Indonesian
Confrontation between 1962 and 1966. The 105 weighed
1,25 tons. When stripped, the heaviest part was the cradle
and recoil system which weighed 269 lbs. A good detachment
could reassemble the gun and get a round away in
The 105 was not designed to be towed extensively, as its
axle was rigid and, being a pack equipment, the shocks and
stresses of movement over rough ground caused considerable
wear to its various parts. In training, therefore, the gun had
to be moved by porte for distances of more than 25 miles.
This was not as great a disadvantage as it might appear as,
more often than not on active service, it came into action by
helicopter or parachute.
||Weight of complete equipment
||Weight of shell
||Year of adoption
|18 pr Mk I
|18 pr Mk II
|18 pr Mk III
|18 pr Mk IV
|18 pr Mk V
|25 pr Mk 1 (18/25 pr)
|25 pr Mk II
|25 pr Mk III
|105mm pack howitzer
L 10 Al
|105mm light gun
1. In this table, the weight of the complete equipment is given. In the
earlier tables gun weight was listed as this was normally an integral
part of the gun designation. Weight behind the team included limber
as well as the complete gun and carriage, and was important as guns
were horse drawn. This factor is less important to-day with mechanical
transport. What is more important is the weight of the complete
equipment on its firing platform, as this weight is vital when helicopter
movement and parachuting are considered.
2. Several charges were available in the case of the 25 pr and 105mm,
so muzzle velocity will vary with each charge. MVs quoted are for
the normal maximum charge used. The 25 pr firing charge super
with increment in the anti-tank role had an MV of 2,000 ft/sec. The
Italian 105mm pack howitzer had seven charges.
3. The 4,2in mortar was in use during World War 11, but by the infantry.
It became a gunner weapon after the war.
4. Three types of anti-tank ammunition are listed AP (armour piercing)
shot, HEAT (high explosive anti-tank), and HESH (high explosive
squash head). AP shot was solid and came in various forms, capped,
with discarding sabot etc. HEAT and HESH are explosive in their
action. The former works on the hollow charge principle where energy
is transformed into a powerful jet which penetrates the armour and
delivers a stream of flame and hot gas into the tank. Britain accepted
this principle for non-rotating projectiles such as the PIAT (Projector,
infantry, anti-tank). HESH ammunition squashes against armour
before detonation to blow off a large ‘scab’ within the tank.
5. ‘Illuminating’ is a better name for ‘Star’. Propaganda leaflets could
also be packed in the 25 pr’s carrier shell, the name for the group
including smoke, star, etc.
6. It may be of interest to the reader to compare this table with those
printed in earlier issues, to compare the progress made in effectiveness
of field artillery over 100 years. The 105mm light gun, the British
Army’s latest, is included for comparative purposes.
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