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Site Visit – Ide Hill Ammunition Park

As the war in Europe intensified and the struggle for the protection of Britain grew, so did the need for the storage of more and more ammunition. Storage predictions proved difficult, and soon the new but limited RAF underground storage sites became overwhelmed and the introduction of Air Ammunition Parks sought to alleviate this pressure. I have already written about one such park in a quarry at Snodland, and explored another temporary woodland depot in Mereworth Woods, but my research has led me to another similar site at Ide hill, on the Montreal Estate near Sevenoaks. 

It is unclear when Ide Hill was constructed and came into use, but it would have been around or after the time when Air Ammunition Parks were renamed Forward Ammunition Depots (FAD) in 1941. From the Montreal Park residents history page, “the Army requisitioned Montreal Park as a training camp and did not move out until 11 years later;” halting construction of the estate until 1952 (1952 – 11 years = 1941). This camp, recorded as a Royal Engineer Camp was occupied by the US Army 72nd Medium Regiment, the 24th & 28th Ordnance Bomb Disposal Squadrons.

The approach to ammunition storage had changed at this stage in the war from vast underground networks to temporary forest and roadside storage relying on the woodland for camouflage and dispersed storage clusters as protection to minimise damage as a result of air attack. The standard construction of these new facilities was 9ft wide concrete tracks, and either open air storage bays, or in some cases open ended Nissen Huts. 

While storage may already have been taking place at Ide Hill before preparation for D-Day, one local resident recalled that in”1944 It became obvious military moves were afoot early during the summer. Open-ended Nissen huts appeared by the road to Ide Hill followed by the storage of ammunition and crates of explosives but no guards.” Contributed by A7431347 to the BBC WW2 People’s War, an online archive of wartime memories contributed by members of the public and gathered by the BBC. The archive can be found at

Location and Aerial Photographs

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The site at Ide Hill is expansive stretching over 3km end to end by 2km wide, with around eighty eight visible ‘clusters’ of storage bays, and seven emergency water tanks (still extant). Very little remains today, the temporary nature of the camp resulting in a very rapid demolition. However, most of the tracks are still in use as walkways and access roads to the estate and farmland, and the brick built water tanks still remain. 

1946 aerial photographs from the RAF survey of Britain. There are 88 ‘clusters’ marked, including 7 emergency water tanks, most visible as clearings in the forests. Tracks are minimal, with a strict traffic system most likely in place throughout the site © Google Maps 2018
Montreal Camp, recorded as a Royal Engineer Camp was occupied by the US Army 72nd Medium Regiment, the 24th & 28th Ordnance Bomb Disposal Squadrons. The beginnings of the Montreal Estate can be seen to the right of the image, with work ceasing early in the war as the Army requisitioned the land. This is the probably camp in support of the ammunition depot in the woods to the south © Google Maps 2018

Site Visit

I visited the site a number of times in the summer of 2018, exploring the estate via the numerous public footpaths and trials throughout – many of which are the tracks and roads that serviced the depot. While not much remains in terms of the depot buildings, other clues tell of the sites previous use.

Ide Hill Ammunition Park

Notes on Ammunition Storage

The basic principles of storing military ammunition have been applied since the rapid development of large calibre guns in the 18th Century; and little has changed. However during WW2 the urgent requirement to store vast quantities of munitions often led to the rules being rewritten to support operations, but the development of new explosives less sensitive than the traditional TNT, and cartridged propellants and powders as opposed to barrels of ‘gun powder’ meant that the sensitivities of working with naked flames in confined spaces along side highly flammable munitions became less of a burden. I will attempt to explain very briefly the development of munition storage in support of war operations, based on a series of photographs I have taken from various magazines (military term applied to a building storing explosives) across the UK.

A great image for comparison of the magazine complex at Lodge Hill / Chattenden, Kent. This complex has been designed with safety in mind. The large high explosive stores have been widely spaced, with large earth traverses surrounding them, mitigating against high velocity fragments from one exploding store causing damage (and ultimately preventing sympathetic detonation) of nearby storehouses. Smaller stores are located in the centre, and these would have been for less energetic stores – small arms ammunition, pyrotechnics, grenades, etc. 
The late 19th Century store houses on St Marys Marshes, Kent, were designed to store raw explosive material following manufacture. Constructed in neat rows, the ‘Explosive Store Houses’ (ESH) would have been surrounded by an earth bank (as seen above) and their roofs would have been frangible in that they would have blow out first, directing any blast upwards and not sideways into other stores. Each house was also wood lined and had a suspended wooden floor, important to both enable air circulation and prevent damp setting in to the powders, but the wooden cladding reduced the chance of sparks from hobnail boots. The site is also situated on marshland away from habitation. Safety was the primary aim rather than security.
Fort Dunree, County Donegal. Ammunition and powder storage in forts designed to withstand enemy shelling was solved in one way – go deep. Most coastal forts of the Victorian era had subterranean magazines. This caused problems of their own, damp being prevalent, but also the added logistical burden of having to lift the munitions to the surface when required. Most guns had ‘ready use lockers’ surrounding them, containing ammunition for immediate use, while resupply could be achieved by use of a mechanical lift to the surface. It is also important to note here, that the large calibre guns would have utilised bagged powder and separate shells and fuzes. These three components only came together on the surface when they were ready to be used. Subterranean storage of the three items was separate, and here you can see a powder store. The head-level recesses in the wall are for oil lamps, the only source of light, and they would be isolated by a window so no naked flame was present in the powder store. The floor-level hatches are for the issue and receipt of munitions into the store. The walls and floors are stone / concrete, so the risk of sparking from hobnail boots was severe – to solve this, magazines of this type had a ‘shifting lobby’ where ammunition workers would change their clothes and footwear prior to entering the magazines. This would also provide a physical barrier to others inadvertently entering. 
Fort Burgoyne Main Magazine, Kent. Constructed in around 1860, the fort was built in support of Dover Castle and port. The main magazine of the fort was constructed in support of medium sized guns, and to deal with powder propellants. Suspended wooden floor for ventilation and to prevent sparking, the magazine is constructed into a natural hillside resulting in a deep overhead cover of earth. There is no facility to lift powder or ammunition to the surface from the magazine, but the construction of the fort enables this to be undertaken outside. The lamp recesses are visible at the ends of the vaulted brick room, these would have serviced externally via a small corridor, accessed from a different location. The pipes on the wall to the right are later electric heaters, as is the light fitting hanging from the ceiling.
Cobham Anti-Aircraft Battery, Kent was constructed in 1940 and would have stored ammunition for the four 4.5 inch Quick Fire (QF) guns of the battery. This ammunition was fixed and cartridged (ie; it had a brass cartridge containing propellant, an explosive warhead and a fuze already fitted). The risks of exposed propellant and explosive were reduced, as were the risks from sparks. Given the relatively small size of the ammunition, any accidental detonation would be limited and other than fire, the detonation would most likely not spread to other ammunition. The magazine here is constructed from reinforced concrete. This was not to protect people nearby from accidental explosion, but to protect the ammunition in the store from direct hit from enemy bombing. Steel doors and shutters were to ensure the ammunition was securely stored.
Fincairn Glen Ammunition Depot, County Londonderry. A WW2 and post-war American store house semi-sunken into the ground, and covered with earth. This ammunition depot was constructed inside a deep glen, giving good protection from view and also aerial bombing.
Kilnappy Ammunition Depot, County Londonderry. A post-war magazine made from reinforced concrete. The roof would have been frangible and would have blown out in the event of an accidental detonation. The wall to the front was to prevent hot or high-velocity fragments from any detonation escaping and damaging other store houses. At this stage there was minimal threat from air bombing, so explosive safety was primary as opposed to safety from bombing.