The Ordnance QF 25-pounder, or more simply 25-pounder or 25-pdr, with a calibre of 3.45 inches (87.6 mm), was a piece of field artillery used by British and Commonwealth forces in the Second World War.

Durable, easy to operate and versatile,[2] it was the most produced and used British field gun and gun-howitzer during the war.

It remained the British Army's primary artillery field piece well into the 1960s, with smaller numbers used in training units until the 1980s.

Many Commonwealth countries used theirs in active or reserve service until about the 1970s, and ammunition for the weapon is currently (2020s) being produced by Pakistan Ordnance Factories.

The basic idea was to build one weapon with the high velocity of the 18-pounder and the variable propelling charges of the howitzer, firing a shell about halfway between the two in size, around 3.5–4.0 inches (89–102 mm) of about 30 pounds (14 kg).

This platform transferred most of the recoil forces to the ground, instead of using the spade at the end of the trail, making the gun very stable when firing.

In British terminology, the 25-pounder was called "quick firing" (QF), originally because the cartridge case provided rapid loading compared with bag charges, and was automatically released when the breech was opened.

Subsequently, another type of increment was introduced to be added to charges one and two to provide additional combinations for use in high angle fire.

Australia also built complete guns, choosing to weld the carriages rather than rivet, as was the practice in the UK and Canada.

For anti-tank use, the 25-pounder was also supplied with a limited amount of 20 pounds (9.1 kg) solid armour-piercing (AP) shot, later replaced with a more potent version with a ballistic cap (APBC).

The 25-pounder was the main field artillery weapon used by British Commonwealth and colonial infantry and armoured divisions of all types during the Second World War.

The early 18- and 25-pounders had been towed in the field by the Morris CDSW or the earlier Vickers Light Dragon Mk.

Throughout most of the Second World War, the 25-pounder was normally towed, with its limber, behind a 4×4 field artillery tractor called a "quad".

These were manufactured by Morris, Guy and Karrier in England, and, in greater numbers, as the Canadian Military Pattern field artillery tractor by Ford and Chevrolet in Canada.

In the 1950s, the British Army replaced the various "quads" with a new Bedford three-ton gun tower fitted with a specialist body.

This mount proved unsatisfactory and the Bishops were replaced in 1942 by the American M7 Priest, which did not use the 25-Pounder complicating the supply of ammunition in the field.

By Second World War standards, the 25-pounder had a smaller calibre and lower shell-weight than many other field-artillery weapons, although it had longer range than most.

[9] In UK service, during the 1960s, most 25-pounders were replaced by the 105mm Abbot SPG, some by the Oto Melara 105mm pack howitzer, and the remainder by the 105mm L118 light gun.

The last British military unit to fire the 25-pounder in its field role (as opposed to ceremonial use) was the Gun Troop of the Honourable Artillery Company on Salisbury Plain in 1992.

[15] Domestic production allowed the 25-pounder to be mounted in Australian-produced vehicles, such as the Thunderbolt tank [16] and the post-war self-propelled gun, the Yeramba.

This led to Australian development of a short-barrelled lighter version which was more suitable for off-road deployment, as required, e.g., in the New Guinea campaign.

It was extensively used in the early stages of the South African Border War, including Operation Savannah.

It was replaced by 122 mm Type 60 howitzers, but still remains in service with the Ceremonial Saluting Battery of the 6th Field Regiment.

[21][22] In 1949, 48 ex-British-Army Mark III 25-pounders were acquired by the Irish Defence Forces and were in service with the reserves until 2009, having been replaced in the army by the 105 mm Light Gun in 1981.

Following Greece's entry into NATO in 1952 and the standardization on American calibres in 1953, the 25-pounders, unlike other models, were not retired but reorganised into 13 battalions of eight guns each, as part of divisional artillery formations.

The 16th Field Regiment of the Royal New Zealand Artillery, equipped with 25-pounders, was formed to join the United Nations force in the Korean War.

[24] A 2015 news report shows at least one 25-pounder in service with Kurdish Peshmerga forces, employed against ISIS positions in Mosul, Iraq.

It had Probert-pattern calibrating sights, but with the range indicator wrapped into the distinctive cone that rotated against a fixed reader arm.

139th (4th London) Jungle Field Regiment used the modified guns and developed procedures for dismantling them for stowage aboard Douglas C-47 Dakota transport aircraft.

The Mark III carriage, also narrow, was a further development of the Mark II carriage to provide joints that enabled the trail to be cranked for "upper register" (high-angle) fire to avoid the need to dig a trail pit, and used with the cranked "dial sight adaptor" previously adopted for high-angle fire.