Gen Brooke: Anti-tank Islands

General Brooke’s view was that swift offensive action was the only measure to counter any German invasion. He considered that the correct policy was to create mobile reserves to be held near the coast ready to counter attack the enemy immediately and drive him back into the sea before he had time to consolidate.


On July 22nd on a visit to Eastern Command he noted in his diary: “I also discovered that much work and energy was being expanded on an extensive system of rear defence, comprising an ant-tank ditch and pill-boxes, running roughly parallel to the coast and situated well inland. This static rear-line did not fall in with my conception…..To start with, we had not got sufficient forces to man this line, even if we had wanted to do so. To my mind our defence should be of a far more mobile and offensive nature. I visualized a light line of defence along the beaches, to hamper and delay landings to the maximum, and in rear highly mobile forces trained to immediate aggressive action intended to concentrate and attack any landings before they had time to become too well established. I was also relying on heavy air-attacks on the points of landing…..”


On a meeting with G.O.C‘s Army Commands on Aug 6th Brooke stated “The idea of linear defence must be stamped out; mobile offensive action must be the basis of our defence. What is required to meet the dual threat of seaborne and airborne attack is all-round defence with the maximum number of troops trained and disposed for rapid counter-offensive”.


Churchill was in complete agreement – in a minute dated 5th August, “Defence against Invasion”, he noted that the first lines of defence were active patrolling by air of possible invasion ports and immediate attack on concentration of enemy shipping. Should the enemy succeed in landing he should be attacked by sea and air making it impossible to reinforce his lodgments. The enemy was to be delayed in the area of beaches as long as possible allowing counter attack troops to move up: “The defence of any part of the coast must be measured not by the forces on the coast, but by the number of hours within which strong counter-attack by mobile troops can be brought upon the landing places. Such attacks should be hurled with the utmost fury at the enemy at his weakest moment, which is not, as is sometimes suggested, when actually getting out of his boats, but when sprawled upon the shore with his communications cut and supplies running short.”


On Aug 3rd GHQ Home Forces instructed Scottish and Northern Commands there was no longer any requirement to continue developing the GHQ Stop Line.  Southern, Aldershot and Eastern Command received the same instructions five days later, although work in hand was to be completed. The GHQ Line in the area of Southern, Aldershot and Eastern Commands was actually almost complete and could act as an anti-tank stop line. GHQ still required the maintenance of the GHQ Line for operational purposes and responsibility for it was transferred to the Sub Area Commands. Plans were put in place to hold it with Home Guard units and other Sub Area personnel based in the rear areas.


The artillery policy also changed – the anti-tank guns allocated to the GHQ line were now utilized for beach defence and the Field Artillery also began to take on a more mobile defence role.


The whole defence layout was moved nearer to the coast. The GHQ reserves were moved to Cambridge, Hertfordshire and Surrey, reducing the distance to the coast by about half.  






























                                                  Above: GHQ Reserves, Sept 1940


Work on Corps and Division Stop lines was also largely halted. Again the defences on these lines were to be maintained for operational purposes with the responsibility also being transferred to the Sub Area Commands.


Early in 1941 GHQ Home Forces ordered the Army Commands to abandon the concept of manning the GHQ Stop Line. Defence inland was now to be based on nodal points (i.e. locations of principal road junctions) given strong all-round defence. The more important communication centers were to be fortified as “anti-tank islands”. Military Training Pamphlet No 23, Operations Part II – The Infantry Division In Defence sets out this general principal: “It must be remembered that the modern battle is largely fought along the road systems. Defended anti-tank localities should be sited to deny the use of the roads to the enemy, and will be formed by linking up such natural obstacles as woods, villages, or groups of houses”.


There were three levels to the new policy (although not every Command used this terminology):


• Anti-tank islands – formed at important centers of communication (usually towns) with a view to denying these communications to the enemy especially his Armoured Fighting Vehicles (AVF). To be formed only in areas where there is a strong enough Home Guard garrison to allow an all round defence.  Defences would consist of an anti-tank obstacle consisting of buildings of the town, natural obstacles, artificial obstacles such as ditches and minefields. Strong points (pillboxes, fortified buildings, earthworks) covered the obstacle. They were not to be regarded as fortresses to withstand a siege. They were expected only to be able to hold out against the leading elements of the enemy. Civil preparations were put in place to allow them to be self sufficient.


• Centers of resistance – these were to be set up at certain points on key routes likely to be used by the enemy. Defences would not be as substantial as anti-tank islands and would consist of road blocks and arrangements made to attack any stalled enemy AFV’s.


• Defiles – these were key routes that any mobile forces would use in order to deploy and counter attack the enemy. They were expected to be likely targets for bombing attacks by the enemy. Arrangements were to be made for passive air defence, road clearing and medical facilities.


Although work on the GHQ Zone of stops and Corps / Division Stop Lines had been halted many of the defences constructed were incorporated into the defence of nodal points and “anti-tank islands”.


Despite the change of policy, during the autumn / winter 1940 and into early 1941 Brooke still faced the same problems as Ironside: a large body of untrained troops and lack of equipment. The lack of transport was a key problem given his strategy relied on mobility for counter attacks. Home Forces still relied heavily on motor coaches to move troops around – now formed into Motor Coach Companies under the RASC. On the day he took command of Home Forces he reflected on the gravity of the situation given “the unpreparedness of our defences, the appalling lack of equipment, and deficiency of training and battle-worthiness in the majority of our formations”.  Matters were not helped when Brooke was informed on Aug 8th that one regiment of heavy, one of light and one of cruiser tanks were to be sent to reinforce General Wavell to halt the Italian advance on Alexandria. Brooke was far from confident in defeating the German invasion, now anticipated during September.


Even into 1941 Brooke noted “I raised the lamentable lack of arms that still prevailed after one and a half years of war………This did not please Winston”.




Ironsides Line, C Alexander, Historic Military Press, 1998

The Turn of The Tide, A Bryant, Collins, 1957

Defence Plans of the United Kingdom, TNA

Cabinet papers, TNA

Anti-Tank Islands and Centers of Resistance, TNA

Military Training Pamphlet No 23 – Operations Part II The Infantry Division in Defence, The War Office, 1942