The 25 Pounder saw active service in Malaya and Singapore during the war with Japan. None were at Fort Siloso.
The 25 Pounder Gun-Howitzer was originally designed as a dual role weapon, a traditional field gun with its relatively flat trajectory, and that of a howitzer with its high angle of fire. The 25 Pounder was developed from the 18 Pounder which saw extensive service in the First World War. The first 25 Pounders, Mark 1s, were a conversion from 18-Pounders. The Mark II entered British service in 1940, and remained In British service until 1967, when it was relegated to training units.
The gun proved to be one of the best field guns of its type, serving as a field gun, howitzer and anti-tank gun. It was even mounted as a self-propelled gun, Three versions being made; The British ‘Bishop’, the Australian ‘Yeramba, and the Canadian ‘Sexton’’. All on tank chassis, Valentine, Lee and Ram/Grizzly respectively. The gun went on to serve with many armies around the world, including the Singapore Artillery.
The gun was very mobile and, until the 1950s in the British Army was normally towed with its Limber (a two wheeled cart generally carrying 32 rounds of ammunition) behind a 4x4 tractor called a ‘Quad’.
The gun is of steel construction, with an autofrettaged loose liner for the tube. Autofrettage is a metalworking technique that applies only to components subject to pressures above 15,000 psi. Common examples include gun barrels and their liners. The barrel is rifled with 26 grooves, with a calibre of 3.45 inches (87.6 mm). Sighting was by means of Dial Sights, or for direct action a Sighting Telescope was used. There were several versions of each of these sights.
The Carriage is a Box Trail and Platform type. The carriage allows the barrel to elevate from -5° to 45°. An adaptor to the Dial Sight combined with using a trail pit or wheel mounds, allow the elevation to reach 70°. The traverse of the gun is 4° left and right. When mounted the Traversing Platform, 360° traverse is possible. The Platform is circular and the gun’s wheels rest on it. It was attached to the underside of the Carriage and lowered to the ground when required. The gun assembly weighted 3,600 lbs (1,633 kg)
The gun used separate or two-part ammunition. The shell and cartridge case containing the propellant charge and primer were loaded into the breech separately.
The gun mainly fired H.E. (High Explosive) shells. Other ammunition types included A.P. (Armour Piercing), Smoke, and Star-shell. The shell with fuze weighed 25 pounds (11.4 Kg).
The usual charge in the cartridge case was contained in three charge bags coloured red, white and blue. This enabled the use of varying propellant charges. All three bags constituted Charge 3, Red and white bags gave Charge 2 and the red bag gave Charge 1. There was also a ‘Supercharge’ cartridge containing one charge only. There were several different types of propellant charge.
The range of the gun was of 11,500 yards (10515 metres), but with supercharge could achieve 13,400 yards (12,344 metres).
The rates of fire were:
Gunfire, 6–8 rpm (rounds per minute)
Intense, 5 rpm
Rapid, 4 rpm
Normal, 3 rpm
Slow, 2 rpm
The normal gun detachment was:
No 1. Normally a Sergeant. The Detachment Commander.
No 2. Breech operation and ramming the shell.
No 3. Gun layer.
No 4. Loader
No 5. Ammunition supply
No 6. Ammunition supplier. He was also usually the second in command. He had responsibility for the preparation of ammunition and setting the fuze.
The last use of the 25-Pounder by the British army was at the Battle for Mirbat in Oman on 19th July 1972. It was fired over open sights at attacking rebel forces. The gunner, SAS Sergeant Talaiasi Labalaba was killed during the action. He was awarded a posthumous Mentioned in Dispatches. Some of his his comrades campaigned for him to be awarded a much higher award, The Victoria Cross - but without success.