Early 20th Century Anti-Invasion Defences of the Forth

Introduction

“The problem of Home defence is part of the greater problem of Imperial Defence…it is obvious that the United Kingdom should be adequately defended, because a successful blow struck at the heart of the Empire would be more instantly fatal than any other form of attack.”

At the beginning of the 20th century the British Army began to plan systematically against the invasion of the east coast of Scotland, at first from a range of European enemies, but increasingly in the face of a perceived growing threat from Germany. Much of what was planned and built in the Second World War reflected earlier arrangements but there is no evidence that those in charge in the later war were aware of their predecessors’ work .

The defences planned in Scotland were a development of arrangements made in southern England from the 1880s, when the perceived threat was a French attack on London. The extension of defences to the east coast of Scotland reflected growing concerns about the vulnerability to a German attack.

The Riddle of the Sands by Erskine Childers was one of a number of ‘invasion novels’ written between 1871 (The Battle of Dorking) and 1914 , based on the premise that a continental power (usually Germany) was planning or had undertaken a surprise attack on the largely unprotected east coast of Britain.  These novels reflected, and indeed helped to fuel, the growing commercial and naval rivalry and tension between Britain and Germany.

Location map, showing the main anti-invasion features.

Background

The defence of the coast of the ‘German Sea’, as the North Sea was known until 1914, was the responsibility of the navy and the army in their respective maritime and terrestrial spheres.  In general, there was almost no coordination of their wider roles but coast defence was one of the few areas in which the War Office and the Admiralty had to work together; coordinated planning was achieved between 1890 and 1903 by the Joint Naval and Military Committee on Defence and, in 1903–4, by a series of joint conferences to discuss the nature and scale of defence required, mainly at naval and commercial ports

The army built and manned the coast artillery batteries while the navy managed the maritime defences – booms, patrol vessels, the Examination Service and, later, anti-submarine and anti- torpedo nets.

The oddity was submarine mining, which was an army responsibility until 1905 and then, when revived in the First World War, a naval one. ‘Submarine mining’ was a defensive weapon developed in the mid-19th century and implemented in the UK from the 1870s until 1905, by a Volunteer branch of the Royal Engineers. When an attack was believed to be imminent the local mining company would arm its mines and lay them in a pre-arranged site. An operator on shore, keeping the minefield under observation, could set off a group of mines if an enemy vessel was detected in the minefield.

The strength of the coast defences in the Forth between 1902 and 1918 is summarised in this table.

Defence Schemes

The Army took the threat of invasion and of attacks on its coast batteries sufficiently seriously, that from 1899 it prepared and printed complex ‘Defence Schemes’ for parts of the United Kingdom.

1900 Defence Scheme

The 1900 scheme described Edinburgh as ‘after Glasgow, the largest and most important city in Scotland’ which ‘might form a tempting object of attack if undefended’. The Forth at this time was not to be ‘a regular naval station’ in time of war but was a centre for naval signalling and contained several ports vulnerable to hit-and-run attacks. Attacks on Edinburgh or Leith were expected. Key installations were identified: the batteries at Kinghorn and Inchkeith; the submarine mining establishment and its attendant batteries at North Queensferry; the Forth Bridge. To repel land attacks, Edinburgh, the Forth and Fife were to have about 7,500 Volunteers (including 1,579 artillery, 120 cavalry, and 475 engineers) plus the regular infantry battalion garrisoning Edinburgh Castle.

1905 Defence Scheme

In 1903, the creation of Rosyth Dockyard was announced, so by 1905 the Forth was a ‘Secondary Naval Base’ at a risk in the “Precautionary Perioed” i.e. the run up to war, of ‘minor raids by a few daring men for the purpose of damaging docks, lights, bridges, and batteries or vulnerable points on the coast’.
In the ‘War Period’ attack by cruisers or torpedo boats to damage docks and shipping or an attack on Edinburgh or the batteries of the Forth by a landing party of 2,000 men, supported by cruisers were anticipated.
The potential embarkation ports were named as Dunkirk (France), Wilhelmshaven and Kiel (both in Germany). Land forces of 11,704 men (mainly auxiliary) were identified as being available to protect the coasts of the Forth estuary and the coast batteries.

1907 Defence Scheme

The Rosyth Dockyard project had been subject to political debate and uncertainty, so in the 1907 scheme the Forth had reverted to being a ‘Defended Commercial Port’. During the Precautionary Period attacks were to be prepared against at Kinghorn Battery; Coastguard Battery, Carlingnose Battery and the north end of the Forth Bridge; Dalmeny Battery and searchlights, the south end of the Forth Bridge; and the island of Inchkeith.
The docks at Leith, Granton and Burntisland were to be defended by the local police force.
In the War Period the type of attack to be prepared for was very much as set out in 1905.
The forces available to the Fortress Commander were 321 Imperial Yeomanry, 232 artillerymen in the fixed defences (which had been radically reduced by the Owen Committee in 1905–6), 232 artillerymen in two field artillery batteries, each of four 15- pdr guns, and 5,523 infantry, mainly auxiliaries. The garrison of Inchkeith was only to be 134 officers and men, reduced from the previous plan to have 200 men.

1909 Defence Scheme

Although the contracts to build Rosyth Dockyard had finally been awarded, the planned completion date was 1916, so in 1909, the Forth was still considered a Defended Commercial Port, that would ‘probably be used as an anchorage for the Fleet in time of war. The estuary was now at risk of a attacks to destroy docks and shipping, the Forth Bridge, the works of defence and electric lights, warships at anchor and works at the naval base.
Infantry detachments were allocated to protect the coast batteries. Inchkeith had the largest garrison, with 660 infantrymen (over four times larger than in 1907), while Inchgarvie had 41. A general reserve of four battalions of infantry was held in Edinburgh with 12 15-pdr field guns in two batteries.
The commander at Kinghorn and Burntisland was instructed to prepare a line of defensive positions north of Kinghorn, while the commander on Inchkeith was instructed to prepare shelter and positions for his large infantry garrison.

The beaches identified as practicable for enemy landings were shown in this map.

Forth Coast Defences in 1909 – beaches marked in red were potential invasions sites.

1912 Defence Scheme

The 1912 document was prepared by Scottish Command in Edinburgh and covered the whole of Scotland. The 1909 defence schemes of the individual defended ports (the Forth, Clyde, Tay and Aberdeen) were included in this Command-wide scheme. Large-scale invasion of Scotland was not envisaged. The two most important targets were considered to be the Rosyth naval base and the Forth generally, and the Clyde and its ship-building industry.

It was feared that landings might be attempted against the two main targets on the Forth by landings on either shore but more likely on the north. The Forth was provided with a reserve of Territorial troops comprising the Lothian Infantry Brigade, Royal Engineers and Royal Artillery.

Apart from the local garrisons, the army in Scotland was split into two groups. One force, was to be held in reserve and could operate against any major landing. The other was the ‘Local Force’, which was to be based around central Scotland in places that would allow it to concentrate and move against landings either in the east or the west. Significant elements were stationed near Stirling, Larbert and Dunfermline, from where the rail network could move men and equipment rapidly to wherever they were needed.

Defences Planned or Built, 1914–18

Early in the First World War anti-invasion defences were built, and the batteries listed in the previous section had their landward defences put in place or extended.

There is very little evidence – physical or photographic – to confirm how many of the defences, beyond the gun batteries and defence lights – were actually built. It is possible that they were only lightly manned by locally based troops. However, the that they were mapped in 1915–16 suggests that they were not abandoned

Plans for specific location in the Forth

Fife shore

Fife Ness (Naval Radio Station)
Largo Bay
Methil–Balgonie line
Around and inland from Kinghorn
Inchkeith
Downing Point battery
Braefoot battery
The Crombie Royal Naval Armaments Depot
The northern approaches to the Forth Bridge, incorporating the defences of Carlingnose and Coastguard batteries, Rosyth Dockyard, and Castlandhill Naval Radio Station

Lothian shore

The southern approaches to the Forth Bridge, incorporating the defences of the Dalmeny
Hound Point
Blackness Castle
The beaches west of Dunbar
Beaches to the north and north-west of Gullane
The coast at Prestongrange
Edinburgh