Two types of Japanese guns are on display at Fort Siloso. They have been named after locations where they were found; Mandai and Seletar. The Japanese were mounting these as part of their preparations for the expected British return in force.
The four ‘Seletar Guns’ are Japanese 120mm Dual Purpose Naval Guns. They were discovered in the forest reserve to the east of the Pierce Reservoir in 1979. These guns were electrically operated, and when found were complete with their control centre. Remains of cable and wiring were found in the control centre and leading to the guns. They were mounted at Fort Siloso in 1981.
These guns are thought to have been manufactured in Japan by the Kure Arsenal in 1944. They were designed for both artillery and anti-aircraft purposes. The guns were mounted on several different types of warship, including aircraft carriers, cruisers, escort vessels and auxiliary vessels.
Shells for the gun weighed 20.3 kg and the propellant charge was 5.5 kg. A complete round of ammunition consisting of the shell, propellant, primer and cartridge case weighed 34 kg.
The gun had a maximum rate of fire of 11 rounds per minute to a range of up to 16,000 metres, with the barrel elevated at 33°
It is known that many of this type of gun ended the war as defensive land based artillery, either as a single mounted gun, as found in Singapore, or in twin turret naval mounts.
The two guns on display are said to have been found in the Mandai jungle in the north of Singapore by officer cadets of the Singapore Armed Forces Training Institute in 1966.
However, David Tisdale contacted me and wrote:-
In 1966 I was a student at Bourne School Singapore and undertook, along with many other pupils, jungle trekking as part of the Outward Bound courses held there. On one such expedition my party lost its way, I believe on what we called ‘Mandai 2’. Going off track we found one gun barrel semi-buried, which at first we mistook for a fallen tree. Shortly afterwards we discovered a whole gun standing in a small clearing in a dip in the ground. Two Raja Brookes butterflies were circling the raised gun barrel. There did not appear to be a breech block.
We reported the find to our teachers and they in turn informed the British Army, who came to the school to ask us for more details. Unfortunately, being lost at the time, we could be of little help as to their exact location and I have no idea whether those particular guns were ever located.
Were these the Mandai Guns, or some others? Does any one have any further information?
The Mandai guns were 140mm naval guns. This type of gun served as secondary armament on capital ships, and primary guns on smaller ships of the Imperial Japanese Navy. It was also extensively used in the coast defence role. The gun was mounted on a single pedestal, single casemated, or in a twin turret.
The gun used Q.F. Separate Ammunition. The shell was loaded into the breech first, then it was followed by a cartridge case containing the propellant charge and the primer. The shells were armour piercing or high explosive and weighed 38 kg. The propellant charge had two weights, 10.33 kg or 10.97 kg.
At an elevation of 35°, the gun had a range of 20,574 metres. It could fire at a rate of up to 10 rounds per minute.