Source: Operation Sea Lion: GERMAN PLANS FOR THE INVASION OF ENGLAND 1939-1942 by Ronald Wheatley
Appendix A to Army Group A's Order No. 1 for the Execution of Sea Lion (14 September 1940)
If, after fulfilment of the known conditions, orders are issued to carry out Operation Sea Lion, fighting for the English coast and the capture of the first connected bridgehead will probably develop as follows.
The leading assault troops of the advanced units and the first echelons of the first wave will land at dawn in the face of more or less stiff enemy defence.
Where it appears necessary, artificial smoke will be requested by the troops who land as it becomes light. Some days before S-Day known coastal batteries and fortifications will be neutralized, or at least reduced in effectiveness, by the Luftwaffe.
When local bridgeheads have been won, energetic junior commanders will co-ordinate the mixed units and will win important features inland. Gradually weak but coherent fronts will form. These will be increasingly extended by the continual arrival of reinforcements, and will also gradually gain in depth.
Heavy counter-attacks by the enemy, equipped with artillery and heavy weapons, are to be expected very soon. In comparison, our troops will still be weak in numbers and equipment. Stiff fighting will develop. Everything depends on courageous and determined junior commanders, who, exercising strict control over the forces disembarked, must not yield a foot of ground.
Corps and army staffs remaining on the Continent must do their utmost to supply reinforcements to these troops, who will frequently be fighting hard under difficult circumstances. This applies above all to artillery and tanks, as well as ammunition.
Senior commanders with small staffs will cross only when the fighting power of the forces landed has been sufficiently reinforced from the rear. They will leave behind their chiefs of staff or operations officers. Extensive staffs (Corps and Army H.Q.s) may only be sent over after forces required for the fighting have crossed and progress has been made inland.
Thus the higher staffs will only gradually transfer control to the island after some days and the supply of further forces will be carried out by the Continental Command H.Q.s (Heimatstäbe).
Premature crossing of complete higher staffs has no value during the small-scale fighting on the coast, and it endangers the uninterrupted flow of further forces, as of further artillery, heavy weapons, and single tank units. At first, therefore, the initial actions on the coast will be directed largely by battalion, regimental, and divisional commanders: senior commanders will take over later. Also, the restricted area cannot at this time accommodate vehicles, supply columns, and staffs of all kinds.
After daylight on S-Day, but not before, the Luftwaffe will support the main effort of the landing forces, compensating for the lack of artillery. Other units will hinder the movement of enemy reinforcements in southern England. Important railway lines in central or northern England will not be interrupted until later.
Small but complete units of the armoured divisions will be incorporated at an early stage in the first wave, in order to support the infantry.
The larding of complete armoured divisions will take place only when a sufficient area of the island has been won for the use of this arm, which depends for its effect on mass employment. Since landing must necessarily take place on wide fronts, it will be possible to concentrate these divisions only as penetration is effected into the interior.
When the connected bridgehead 20-30 km. deep has been won, days will elapse before a consolidated attack can be launched against the first operational objective.
This gradual development of operations, landing, penetration in-land, and establishment of the bridgehead, is the probable picture of events. If favourable circumstances allow the operation to be speeded up, our very mobile and flexible Command will be able to adapt itself to this favourable situation as quickly as in former operations.