Ammunition bunker

The Department's description

Exterior description and setting

One of 21 ammunition bunkers erected in Fincarn Glen by American military personnel in 1941-42.
Situated at the southern tip of the glen, this single-storey, single-bay structure is aligned NW-SE into the hillside with its entrance at SE. It is of rectangular plan and semicircular cross-section.
All its components are of pre-formed galvanised steel. Its roof and sides are of overlapping curved corrugated sheeting, all completely covered with earth.
The two end walls are of flat steel panels held together with flanges bolted together up their outside faces. These walls have flat tops and sloping sides which extend beyond the roof and sides to retain their earth covering. The back wall (at NW) is dug into the hillside and thus covered with earth as well.
There are two outward-opening steel doors at its SE end, both with a small vent at their bottoms. The metalwork above the doors has been cut away to increase the head height (for vehicle entry) and the doors heightened accordingly. Recent paint has obscured any original markings on the flanking walls.
The right-hand end of the frontage is abutted by a small concrete lean-to. This was possibly an original Second World War building, but has since been greatly altered and enlarged for use as agricultural buildings.
The bunker has recently been refurbished by its owner for use as a garage and domestic store. Its covering vegetation has been removed and it is now covered with bare earth.

Setting:
All the ammo bunkers were widely spaced out along the glen to minimise collateral damage should one have exploded. The nearest to this one are 105m to NE (HB01/06/019I Building 3) and 115m up the slope to NW (HB01/06/019H Building 3).
This example sits at the bottom of a grassy slope rising up the west side of the glen. The stream flowing northwards through the glen runs in front of its entrance, just beyond an unpaved track down the glen. The ground to its immediate SE has been relandscaped as a garden to the nearby bungalow and is enclosed by a low rendered wall.

Historical information

The Fincarn Ammunition Depot was constructed by American military personnel with the assistance of local labour. It was completed by May 1942 and used for the temporary storage of munitions shipped into Lisahally Port on Lough Foyle, 6km to the north. From Fincarn, the ammo was transferred to military bases such as the nearby Maydown and Eglinton airfields.
The steelwork on many of the ammo bunkers bear the legend "Armco Ingot Iron Manufactured by the American Rolling Mill Co Middletown, Ohio 2oz coating". 'Armco' is the acronym of the American Roller Mill Corporation of Middletown Ohio, founded in 1899 and a pioneer of continuous rolled sheet steel production. The name is still used generically to this day to denote cylindrical corrugated metal culverts under roads etc.
This bunker is essentially a standard Armco hut, the size of which was 50ft x 20ft x 10ft radius. Its heavy-duty galvanised steel sheeting and arched cross-section made it capable of being buried under several metres of earth. It is not unlike a Quonset hut, the American equivalent of the British Nissen hut, but without any internal framework and by a different maker.
C Company of the 1st Provisional Marine Battalion, an infantry brigade of the US Marine Corps, was based nearby at Beech Hill and performed guard duty here for a time. The bunkers may also have been used for as a chemical storage depot (known as C-910) between November 1943 and August 1944. It has recently been refurbished as a domestic store and garage by its owner.
Although erected in the early 1940s, no buildings or structures are depicted in Fincarn Glen on the 1948-49 OS map, presumably for security reasons. All the features are, however, shown on the 1963 OS map under the caption "Disused Camp Site".

References - Primary Sources:
1. PRONI OS/6/5/14/5. OS 1:2500 map, Co Londonderry sheet 14-05 (1948-49).
2. PRONI OS/11/37/5/1. OS Irish Grid map sheet 37-05 (1966-67).
3. PRONI OS/11/37/9/1. OS Irish Grid map sheet 37-05 (1968).

Secondary Sources
1. A. Glenfield, Second World War in Northern Ireland, .
2. ARMCO history: ,, and .
3. Quonset huts: J. Decker & C. Chiei (eds), Quonset: Metal Living for a Modern Age (Princetown: Princetown Architectural Press, 2005), and .
4. Chemical storage, .

Criteria for listing: architectural interest

Not listed

Criteria for listing: historic interest

Not listed

Evaluation

This record has now been protected by scheduling under LDY014:014 and can be viewed on the NISMR database:

A corrugated steel ammunition bunker built by the US military authorities in 1941-42 for the temporary storage of ammunition.
This ammo bunker is of architectural interest as a good example of a Second World War ammunition store. Its superstructure is of lightweight pre-fabricated components so that it could be transported easily (across the Atlantic in this case) and quickly erected using unskilled local labour. Its semicircular arch design did away with the need for an internal frame and no foundations were required as it was self-supporting. Pre-fabrication was extensively used during the war for military buildings and structures. Once fabricated, earth dug from its vicinity was used to give the store added protection against blast damage and also camouflaged it. The interior is well preserved although all the maker's marks which are found on the other bunkers has been obliterated.
The bunker's setting is of special note - in a narrow glen which could be easily defended at both ends. The spacing between it and its neighbours - 95+ metres - also minimised any damage should one have exploded. In this case, however, its immediate setting has been compromised by the adjacent bungalow and garden.
The bunker also has considerable group value in being one of 21 ammo stores and one of 24 surviving military structures in Fincarn Glen.
Historically, this bunker had a rare and unusual function. Virtually all its original fabric survives in an unaltered stare. It is a tangible reminder of the large American presence in and around Londonderry during the Second World War. The Fincarn ammo stores are probably the largest surviving concentration of their type anywhere in the Province.
Because of their specialist function, American connection and survival as a group, they are not only of local interest, but of provincial significance as well.