During the weeks immediately preceding the invasion, it was found necessary to introduce a number of special security measures in order to obviate as far as possible the danger of leakage at that critical time. At the end of March the air-mail service between this country and Lisbon was discontinued. 1st April witnessed the imposition of military censorship, of the ban on travel to Ireland and of the visitors’ ban, which prohibited all but residents from visiting certain specified parts of the coast. On 6th April Service leave was stopped; on the 18th travel to and from the United Kingdom was disallowed; finally, on the 24th, a censorship was imposed on all diplomatic mail. While these regulations were being drawn up, the Ops (B) staff had been consulted, so that the needs of deception could be met. At their suggestion the area affected by the visitors’ ban had been extended to satisfy the requirements of the cover operations then in force, and other adjustments had been made. In these preliminary discussions, however, insufficient attention was paid to the desirability of continuing such measures, in support of FORTITUDE, after the invasion had been launched. It was not until 17th May that this aspect of the matter was brought to the forefront, when, at a meeting of the Home Defence Executive, the Deception Staff suggested that the diplomatic ban should be continued at least until D plus 30. This request revealed a deep cleavage of opinion and drew an immediate retort from the Foreign Office representative: ‘He would object very strongly to any suggestion that the diplomatic ban should continue in force after D Day; he would, in fact, never have agreed to the ban except on the understanding that it would cease when OVERLORD had been launched. The Foreign Office were quite certain that, once it was common knowledge that we had landed on the Continent, they would be quite unable to hold the position with either the Allies or the neutrals and, if the proposal was pressed, it would have to go to the Cabinet.’
The matter was referred to the Chiefs of Staff who had already received a note from the Foreign Secretary on the subject. The latter had expressed the view that it would not be possible to continue the diplomatic ban for any length of time after D Day. He had, therefore, suggested that the ban should be lifted not later than D plus two, but that practical obstacles should be imposed whereby diplomatic travellers and uncensored diplomatic communications would not be able in fact to leave the country before D plus seven. This suggestion was accepted by the Chiefs of Staff, and on 30th May another meeting of the Home Defence Executive was called to consider the effect of the withdrawal of the diplomatic ban on other security measures. It had been argued at the previous meeting that its removal would undermine the value of many of these and while this was generally agreed a plea was put forward by the London Controlling Officer that the other restrictions should not be withdrawn en bloc but that their removal should be staggered. The removal of the diplomatic ban would undoubtedly harm FORTITUDE SOUTH, but that was unavoidable. The simultaneous removal of all important restrictions would be disastrous. The meeting recommended that all special security restrictions should be reviewed together on or about D plus twelve.
The decision to withdraw the diplomatic ban put us in an awkward position. If this unprecedented measure had been necessary for the invasion of Normandy it would indeed be hard to understand why it was any less necessary for the equally or perhaps more important attack on the Pas de Calais. We at least had the advantage, however, of knowing that the ban was to be removed in little more than a week and this gave us time to think of an explanation. To meet the difficulty, GARBO, soon after the invasion had been launched, informed Berlin of a dilemma which faced two British Departments of State. The neutrals had accepted the imposition of the ban with reluctance. The impending attack on the Pas de Calais demanded that the restriction should be continued, but this the Foreign Office declared would be impossible unless we gave our reason for wishing to do so: namely that we intended to undertake a second assault. Rather than disclose our operational intentions to neutral diplomatists, the War Office preferred to dispense with the ban and so the Foreign Office was to have its way. That seemed to us at the time a neat way out of the impasse, and it was with a feeling bordering on mortification that we found our message in Krummacher’s file with the comment ‘of no general interest’ (keine allgemeine interesse). However, as no one else in the OKW appears to have seen anything odd in a full restoration of diplomatic privileges just before the second assault was to be launched, Krummacher’s failure to rise to the occasion did not really matter.
In the event the diplomatic ban was continued, through the personal intervention of the Supreme Commander, until 21st June. On 19th June GARBO gave advance information of its removal and amplified his previous report regarding the differences of opinion which had arisen between the two Departments of State.
When asking for an extension of the diplomatic ban the Supreme Commander also requested that all other restrictions, which had been specially imposed for the invasion, should continue until 1st July. To this the War Cabinet agreed on 13th June. It also agreed to the retention of any particular restriction after the end of the month if good cause could be shown. A meeting of the Home Defence Executive was held on 23rd June to consider the matter. Of the numerous security measures which came under review only two were of such special significance as to concern us here, the withdrawal of the visitors’ ban and the restoration of Service leave. The Home Office was naturally anxious to get rid of the visitors’ ban altogether as it caused hardship to the public. SHAEF was willing to agree to its removal west of Southampton. The Chairman of the Home Defence Executive, in his report to the Chiefs of Staff, laid some emphasis on the apparent success which had already been achieved by the cover plan and this carried the necessary weight with the Cabinet, which decided on 7th July to continue the ban between the Wash and Southampton at least until 1st August. It was in fact extended for another month after that and it was not until 6th September that BRUTUS reported to the Germans that it had been lifted altogether.
The restoration of Service leave was also discussed at the Home Defence Executive meeting of 23rd June. The suggestion that leave should be restored to non-operational troops was resisted by SHAEF on the ground that the Germans would not be able to distinguish the type of troops affected and that any report of the resumption of leave would be damaging to FORTITUDE. This view was upheld by the War Cabinet. At the beginning of August, as a result of strong representations from the Service Ministries, SHAEF finally agreed to the full restoration of leave on 15th August. During July an important change took place in the FORTITUDE Order of Battle inasmuch as the real formations were replaced in almost every instance by imaginary ones. Thus it was possible to say without fear of contradiction when 15th August arrived that although leave had been restored to non-operational troops the ban still remained on all FUSAG formations, since these formations did not really exist. ‘It is expected’, reported BRUTUS on 11th August, ‘that seven days’ leave will shortly be restored. These orders do not apply to the forces in FUSAG.’1
The lesser restrictions which had been introduced to safeguard the invasion were removed one by one during the months of July and August. At the end of July the normal airmail service was restored. This made it possible once more to enlist the services of the letter-writing agents for deception.