Prior to the outbreak of war, the only defences actually in place were the fixed defences of the ports. Defence schemes for these ports considered raids only; the question of invasion, defined as “a serious attack, by which an enemy seeks to bring about a decisive issue” was not dealt with. Invasion was to be defeated by the Royal Navy backed up by mobile armies that could be concentrated to counter any landings. To safe guard London, the assumed objective of an invasion, field works were planned which would control the approaches to the city – known as the London Defence Positions. Field works for the London Defence Positions and defended ports were not to be prepared until attack was considered imminent.
By 1915, the decision to entrench along the east and south-east coasts and begin work on the London Defence Positions was taken. Work continued well into 1916, the front line trenches improved and rear positions constructed to support the front line providing an elaborate trench system, complete with dugouts, in places. The entrenchments and open stretches of beach were protected by barbed wire entanglements. The work was carried out by troops and civilian contractors. Those who thought they were training to go overseas were not impressed: "We learnt we were to embark on the task of digging trenches - somewhere in Essex! That put the lid on things, so we considered. We, infantry soldiers, to dig trenches! It couldn't be right. We thought the Engineers, or the Pioneers, or somebody else, did that. Our job was to carry a rifle, and to shoot Germans" - 23rd (Service) Battalion Royal Fusiliers.
In Norfolk, three main and seven intermediate breastworks were constructed from Rocket House to Sparrow Gap, Sherringham. A subsidiary position (consisting of 15 trenches) was constructed from Warborough Hill to 300 yards east of Weybourne Station. A second line (consisting of 22 trenches) was constructed from Gallow Hill to Weybourne Springs Hotel. Sherringham was also entrenched with work starting on a second line during November 1915. Mention is also made of entrenchments at East Runton and Overstrand. Although the Norfolk coast further west was deemed less vulnerable as the salt marshes would have hindered a quick enemy movement inland, defence was not ignored in this area. Sandbag emplacements were constructed on the shingle beach at Cley and Salthouse. These were severely damaged during a north-westerly gale in early November. Work was commenced on the Taverham - Salhouse Defence Line, sited to cover Norwich.
In Suffolk, work began on constructing field works in the vicinity of Harwich soon after war was declared along the lines of the pre-war defence scheme. During 1915 entrenchment began at Lowestoft. The same storm that damaged defences in Norfolk in November is also noted as damaging defences at Lowestoft Denes as well as works to the south at Thorpeness, Aldeburgh and Slaughden. The 2/6th West Yorks constructed an intricate trench system at Corton Cliffs during 1916 in support of the front line trenches that had already been dug.
Right: Defence Works north
Additional trench lines were also dug to add depth to the London Defence Positions sometime in 1916/17.
Artillery also began to appear along the coast. In Suffolk the 2/1st Essex Heavy Battery stationed at Lowestoft and the 2/1st Welsh Heavy Battery stationed at Leiston were armed with six 60-pounders each. In addition field guns from the Home Defence armies could be utilised if necessary. By 1917 additional guns had been installed along Suffolk’s coast. At Gorleston, a 4.7” Q.F. on a Naval mounting and a 15 pounder B.L.C. were emplaced. Additional 15 pounder B.L.C. guns were emplaced at Thorpeness, Dunwich (two guns), the gap south of Easton Broad and Bawdsey (four guns). These guns had a general defence role and would have certainly been able to disrupt enemy landings, in these days before special purpose landing craft. These guns were positioned in simple open emplacements, some on a holdfast.
Above: Left - 15 pdr B.L.C. on a carraige. Right - loading a 60 pdr gun
In Norfolk, two 4.7” Q.F. on travelling carriages were emplaced at Cromer. As in Suffolk 15 pdr B.L.C. guns were sited along the coast with a general defence role; at Salthouse (two guns), Newport, Eccles Beach and Caister. Batteries of six 60-pounders were manned by 2/1st Fife Heavy Battery at Sherringham and 2/1st (Home Counties) Heavy Battery at Mundesley. Perhaps the most unusual mobile artillery was an armoured train stabled at North Walsham. It was armed with two 12 pdr Q.F. and two Maxim machine guns.
Both Clacton and Frinton, Essex, had four 15 pdr B.L.C. emplaced for general defence. Mobile field guns manned by the Provisional Brigades RFA Batteries were stationed at Little Clacton, Frinton-on Sea and Southminster.
At first medium machine guns was in short supply for troops holding the coast; for example 62nd provisional Battalion noted the defence of Runton Gap, Lifeboat Station, Swallow Gap and Sherringham Promenade would be very much strengthened by the provision of machine guns (along with searchlights). Machine guns began to be supplied in increasing numbers from late 1915 onwards. By 1917, it was considered there were sufficient machine guns available for the coastal entrenchments, which covered the open beaches protected with wire entanglements, to make any landings a very costly affair for the enemy.
The trench positions were further strengthened with concrete pillboxes during 1917. A further period of construction took place in the spring of 1918 at the height of the German Spring Offensives. In Norfolk a pillbox line was constructed running from Weybourne through North Walsham and along the line of the River Ant to near Sea Palling while in Suffolk the Hundred River would appear to be have used as a defence line with pillboxes constructed at Latyme Dam and Rushmere. Also in Suffolk pillboxes were constructed to strengthen the defences of Lowestoft and Felixstowe. The beaches north of Felixstowe (Bawdsey and Hollesley) were also defended by pillboxes as this area was deemed to be only a three to five days march to London. Pillboxes were also constructed in the rear of the beach defences to guard important exits from the beaches and routes inland (e.g. Great Yarmouth, Southwold, Kessingland and Friston). Pillboxes were often sited in pairs to give mutual support. Some of these pillboxes would be incorporated into the Second War anti-invasion defences.