The Fortess Companies at the start of the war

On 1 August 1914 there were 11 Fortress Companies at home and 15 overseas, all on coastal defence duties. Some were entirely for Electric Light (that is, searchlight) duty; others also had Works responsibilities. On mobilisation, men of the Territorial RE took over the home stations, releasing men for duty with the British Expeditionary Force - although not all regulars were withdrawn right away but were released gradually, their places being filled by men who were unfit for overseas service. Territorial troops also moved out to take over some of the overseas stations.

The Fortess Companies histories

Fortress Companies withdrawn from coastal defence work
Company	Notes
1st Company	Based in Gibraltar in 1914. Brought home, converted to an Advanced Park Company and moved to France. Initially replaced in Gibraltar by 1/4th Devon Electric Light Company RE TF (later called 614th Fortress Company RE).
4th Company	Based in Gosport in 1914. Brought home, converted to the 4th Advanced Park Company and moved to Salonika.
15th Company	Based in Gibraltar in 1914. Brought home, converted to 15th Field Company and attached to 8th Division.
24th Company	Based in Malta in 1914. Brought home, converted to a Base Park Company and moved to France.
32nd Company	Based in Gibraltar in 1914. Brought home in December 1914, converted to a Base Park Company and moved to France. Initially replaced in Gibraltar by 1/1st Devon Works Company RE TF (later called 567 Army Troops Company RE).
33rd Company	Based in Cork in 1914. Brought home, converted to the 33rd Base Park Company and moved to Salonika.
47th Company	Based in Capetown in 1914. Brought home, converted to a Base Park Company and moved to Mesopotamia. Details of the unit in South Africa were formed into 358th Special Base Park Company for service in East Africa in September 1917.

Fortress Companies remaining on coastal defence work
Company	Notes
This table is known to be incomplete
28th Company	Based in Malta. Sent a detachment to Salonika in January 1917.
31st Company	Based in Ceylon.
40th Company	Based in Hong Kong.

Fortress Companies of the pre-war Territorial Force
TF Association	Notes
City of Aberdeen	No 1 Fortress Works Company, part of Scottish Coastal Defences. Landed in France 26 April 1915. Later renamed as 552 (Aberdeen) Army Troops Company RE.
Cinque Ports	No 1 Electric Light Company, based in Dover and part of South Eastern Coastal Defences.
Cornwall	Consisting of HQ and No 1 Electric Light Company at Falmouth, No 2 Works Company at Fowey and No 3 Works Company at Penryn, part of South Western Coastal Defences.
Devonshire	Consisting of HQ at Plymouth, No 1 Works Company at Torquay, Nos 2 and 3 Works Companies at Exeter, Nos 4 and 5 Electric Light Companies at Plymouth, part of South Western Coastal Defences.
City of Dundee	No 1 Fortress Works Company, part of Scottish Coastal Defences.
Durham	Consisting of HQ and Nos 1 and 2 Works Companies at Jarrow and No 3 Works company at Gateshead, part of North Eastern Coastal Defences.
City of Edinburgh	Consisting of HQ, No 1 Works Company and No 2 Electric Light Company, part of Scottish Coastal Defences.
Essex	No 1 Electric Light Company, part of Harwich Coastal Defences.
Glamorgan	Consisting of HQ and No 1 Works Company at Cardiff, No 2 Works Company at Barry and No 3 Electric Light Company at Cardiff, part of Western Coastal Defences. Became 556 Army Troops Company RE.
Hampshire	Consisting of HQ, Nos 1 and 2 Works Company at Portsmouth, No 3 Works Company at Eastleigh, No 4 Electric Light Company at Portsmouth, No 5 Electric Light Company at Freshwater and No 6 Electric Light Company at Gosport, part of Southern Coastal Defences.
Kent	Consisting of HQ at the Submarine Mining School at Gillingham, No 1 Works Company at Tonbridge, No 2 Works Company at Ashford, No 3 Works Company and Nos 4 to 6 Electric Light Company at Gillingham, part of Eastern Coastal Defences.
Lancashire	Consisting of HQ and No 1 Works Company and Nos 2 and 3 Electric Light Companies at Aigburth, part of North Western Coastal Defences.
Renfrewshire	Consisting of HQ at Fort Matilda, Greenock, No 1 Works Company at Paisley and No 2 Electric Light Company at Greenock, part of Scottish Coastal Defences.
East Riding	Consisting of HQ, No 1 Works Company and No 2 Electric Light Company at Hull, part of North Eastern Coastal Defences.
North Riding	Consisting of HQ and No 1 Electric Light Company at Middlesbrough, part of North Eastern Coastal Defences.
Sussex	Consisting of HQ and No 1 Works Company at Seaford, part of South Eastern Coastal Defences.
Wiltshire	Consisting of HQ and No 1 Works Company at Swindon, part of Southern Coastal Defences.

Other units on coastal defence work
Company	Notes
London Electrical Engineers RE TF	HQ and six Companies based at 46 Regency Street, Westminster.
Tyne Electrical Engineers RE TF	HQ and four Companies based at North Shields, attached to North Eastern Coastal Defences.

In August 1918, a new establishment was implemented, reorganising into Fortress Companies and Fortress Works Companies. At the same time the Tyne and London Electrical Engineers Companies became the parent units for all coast defence and anti-aircraft Electric Light units and the depots that trained men for them.