Despite the conclusion reached at the end of 1917 that Germany could realistically only land 30,000 men, the Admiralty still considered that Germany could land a force of 70,000. In order to meet further reductions to provide men for the Front, the question as to where reductions could be made in Home Forces was paramount. As no great reductions could be made in the number of troops held to maintain order in Ireland, the “Coast Defence” troops (which were largely comprised of draft finding units) or Anti-aircraft defence, the only reductions could come from the mobile troops. Of the authorised strength of 400,979, the mobile element was 190,045. The Commander-in-Chief considered a reduction of three divisions to five was possible to meet the reduced threat of 70,000 enemy troops landing as against the original estimate of 160,000 troops. A reduction of three divisions would release about 38,000 men leaving a mobile force of force of about 152,000 men.
The General Staff hoped to reduce four divisions in light of the reduced scale of attack and that the Navy now hoped to provide prior warning of an invasion (as opposed to the old schemes which it was assumed the first intimation of invasion would be the appearance of hostile transports off the coast). This would save about 50,000 men.
The Commander-in-Chief Home Forces noted that the Ireland Garrison and mobile forces in Northern and Scottish Command needed to be retained and if the proposed reduction to four divisions took place this would leave a force available in East Anglia of:
Three Cyclist Brigades
Four Mixed Brigades
He considered a Mixed Brigade with a Division in support at Colchester was required for watching the coast south of Harwich. This would leave a force of two Divisions, three Cyclist Brigades and three Mixed Brigades for defence of the coast from Ipswich to the Wash - a force of approximately 53,000 men, substantially less than the 70,000 men the Admiralty considered could be landed.
It was further noted that most troops in the Home Forces Infantry Divisions were young and only partially trained troops while the Mixed Brigades contained a large number of men who were not fit for prolonged activity. The Volunteers were available but could not be employed immediately against any invasion threat. But, at any one time, there were other troops in Britain who were not part of Home Forces but could be utilised to meet any invasion. It was also pointed out that should the naval situation become less favourable to Britain, it would take many months to raise new units to meet an invasion threat. If it was also further decided to send all men under 19 to the Front, there would not even be sufficient troops left for Home Defence to meet the scale of attack of 30,000.
In the first instance, any invasion would have to be met by the Mixed Brigade on the spot. Any one Brigade could be reinforced by a Cyclist Brigade within a few hours and perhaps other Cyclist Brigades at various intervals. The Commander-in-Chief Home Forces considered the risk of reducing the mobile troops by four divisions was acceptable if the estimated enemy force was reduced to 30,000. The War Cabinet confirmed on 6th January “to take the risk of reducing he forces allocated to Home Defence to such strength as would deter an enemy force up to 30,000 men from attempting a landing in this country”. As a result of this decision, the 66th and 71st Divisions were to be broken up in addition to the 72nd and 73rd Divisions. For the defence of East Anglia, this left the following force:
67th Division (Colchester)
68th Division (Bungay)
64th Division (Norwich)
3 Cyclist Brigades (Beccles-Aylsham-Woodbridge)
6 Cyclist Battalions
4 Mixed Brigades (Sherringham-North Walsham-St Olaves-Clacton)
6 Heavy Batteries
On March 21st Germany launched a massive offensive against the British Third and Fifth Armies, the first of a series of attacks planned to break the deadlock on the Western Front. The situation on the Western Front was serious for the Allies, resulting in the need for further reductions in Home Forces to provide desperately needed troops for the Front. In June the Army Council decided to despatch to France all men of A, Bi and Bii category, “fully aware that some dislocation and inconvenience may result”. In addition the mobile troops in Britain were further reduced by the need to reinforce the garrison in Ireland.
General Sir W Robertson, who had replaced Field Marshal French as commanding Home Defence troops (with the new title of General Officer Commanding-in-Chief Great Britain), outlined his concern at these further reductions. He noted the following points:
The mobile infantry divisions had been converted from boys aged between 18 1/3 to 19 years with four months training to boys aged between 18 to 18 ½ years in their first six months of training and were consequently of little fighting value.
The fixed defences of ports had been reduced by the withdrawal of all category A men and the reduction of electric light and artillery personnel to a bare minimum without the provision for casualties or relief.
The Mixed Brigades, the first line of defence, now consisted of mainly of untrained men of low category and were at 50% of establishment.
The Cyclist units, vital for coast watching or immediate reinforcements, had practically ceased to exist until rebuilt by Volunteers.
He further doubted that a scheme drawn up to send home two divisions from France to meet an invasion would be of much practical use as they could not intervene during the crucial first 48 hours of any invasion if little warning was received.
This basically left, with a few exceptions, the troops available for Home Defence those also charged with finding drafts foe overseas, which duty actually took precedence to Home Defence. This resulted in the fact the defence troops in most part consisted of men and boys who had not completed their ordinary course of basic training. The draft finding units with a high turnover meant there were few troops having permanence or a knowledge of Home Defence. In contrast, any invading force was expected to consist of hand picked and highly trained men. During these dark days, the General Officer Commanding-in-Chief Great Britain suggested calling up boys of 17 ½ years age and so allow a return to the system of placing Graduated Battalions in the mobile divisions consisting of boys with four months training and of expanding the use of the Volunteers, some men to be found as a permanent quota for Home Defence (a number of Volunteers were signed on for permanent home defence duties for a period of two or three months until the crises was alleviated).
These considerations required a relatively simple Home Defence Scheme to be drawn up and worked out in detail. The basic principles were that:
Every available gun and rifle was to be used in the event of invasion
The enemy was still to be engaged on the seashore and prevented from disembarkation
If the enemy succeeded in gaining a foothold, all means possible should be used to pin him down on the beaches where he would be hampered by fire from the Navy and finally crushed by reinforcements
Defence schemes should consider the possibility of the enemy penetrating inland and plans should be made accordingly to reconnoitre and if possible prepare rear positions (this was to some extent completed with pillboxes constructed along positions in the rear selected for defence).
In order to meet these principles, troops were to be sited in depth:
Coast Watching units
Support provided by the Cyclist Division, Brigades and Battalions
Local reserves provided by the Graduated Divisions and other troops that may be available
The General Officers Commanding-in-Chief were responsible for mobilization, administration and defence of their respective regions, utilizing all resources within their commands, with the following exceptions:
The General Officer Commanding-in-Chief Eastern Command was also to take responsibility for the defence of London.
The General Officer Commanding 23rd Army Corps, who was directly under GHQ for training, was responsible for the defence of the coast from the Wash (River Nene) to the River Crouch (exclusive of the Harwich defences).
If it was decided to mobilize troops due to the threat of invasion, the code word “Horseguards” was to be issued by telegram. On receipt of this, all defence schemes, emergency schemes and supply schemes were to be put into operation and arrangements made to call out the Volunteers. The East Coast for operational purposes was divided into seven “Theatres of Operations”:
Firth of Forth
Rivers Tyne and Tees
North of the Humber
South of the Humber
East Anglia north
East Anglia south
South of Thames
The Theatre of Operations, South of Thames, was later further divided into Kent and Sussex.
If a warning was received of probable attack, a raised level of alertness but not full mobilization could be ordered under the code word “Kaiyen”. In general all leave was to be cancelled, units on training to return to their formations, and preparatory arrangements made by the RAF to make ready bombing aircraft.
By October, when the question of Home Defence was looked at again, the Allies were on the offensive and the German Armies in full retreat. In view of the difficulties Germany was experiencing in maintaining her Armies on the Continent, it was felt that a maximum of 5,000 men without artillery or transport could be landed. The General Commanding-in-Chief Great Britain considered only draft finding units need be retained for Home Defence. In general East Coast Ports and the Thames and Dover were to be defended as strongly as possible but it was accepted that the remainder of the coast could not be watched and that the balance of Home Forces would have to be maintained inland to be quickly able to move to other threatened areas; the enemy could not be prevented in landing in these areas but would ultimately be crushed.
Above: Home Forces, Suffolk, Oct 1918