As soon as Hitler's forces occupied the Channel Islands he ordered a series of fortifications to defend the only British territory he ever conquered.
The problem was he never stopped, pouring men, concrete and weapons into the Islands until his officers began to refer to his "inselwahn" his island madness and the Channel Islands had become the most fortified place - on earth.
By 1944 the Channel Islands had taken in over 8% of the concrete destined for the Atlantic Wall and had more guns than 600 miles of Normandy Coast. Of the German commanders only Rommel understood the implications for the invasion they all knew was coming.
The German Fortification of the Channel Islands
By Michael Ginns M.B.E.
When their troops landed in the Channel Islands in 1940, Adolf Hitler and the German High Command confidently expected that the war would be over in a matter of a few months, if not weeks; Britain would either sue for peace or be invaded and conquered. Consequently, only token defensive measures were taken to protect the Channel Islands. Sentries were posted at certain bays, whilst machine gun posts and light anti-aircraft batteries were installed to protect the harbours and airports.
By the end of the year, however, with the proposed invasion of Britain postponed indefinitely, Hitler had already turned his thoughts towards Russia but, at the same time, took steps to secure his "back door"; he was certain that Britain would attempt to retake the Channel Islands which, although they would have had no strategic value, would have given the British a much needed (at that time) prestige victory as well as being seen as a gesture of support for the Soviet Union, their new found ally. Hitler accordingly ordered that the defences of the Channel Islands be strengthened and, early in 1941, more anti-aircraft batteries arrived together with some coastal artillery batteries of both the Army and Navy. Several conferences were then held at a high level in Berlin to examine the idea of converting the Islands into strong naval fortresses.
The fortification of the Channel Islands became an obsession with Hitler. In May 1941, he ordered that the 319 Infantry Division be allocated to their defence and that the Division should be reinforced with troops and weapons over and above the strength of a normal first line Division. All this was confirmed on 20 October 1941, when Hitler issued a Directive which laid down that the Channel Islands were to be converted into "impregnable fortresses". Somewhat earlier, experts of the German Army's Fortress Engineer Staff began conducting a tactical, geographical and geological survey to determine the requirements for the forthcoming fortification programme.
In the course of this survey it was soon realised that - bearing in mind the geographical position of the Channel islands and their proximity to France - by placing artillery batteries of sufficient range on the Islands as well as on the French coast, it would be possible to seal off the entire Bay of St. Malo and thus dispense with the need to heavily fortify many kilometres of the adjacent French coastline. Shortly afterwards the Organisation Todt arrived in the Islands with all their construction equipment and a workforce consisting of thousands of foreign workers, either voluntary, forced or slave.
As a result of all this activity, there came to be constructed in Jersey alone no fewer than seven medium coastal artillery batteries mounting weapons with calibres ranging from 10.5cm to 22cm; six light (10cm) field howitzer batteries; six medium and twenty five light anti-aircraft batteries, mounting between them over 100 weapons of 2cm, 3.7cm, and 8.8cm calibre.
For the infantry there were more than 80 field guns and anti-tank guns in concrete bunkers, plus 51 tank turrets mounted on the so-called Tobruk emplacements. This formidable array of weaponry was housed in more than 250 concrete bunkers, this figure including subterranean command posts, coastal observation towers and communications centres. To the foregoing should be added 7,397 metres of anti-tank walls on the beaches, 67,000 land mines, and 23,495 square metres of floor storage space created in the many tunnels that were excavated.
In Guernsey there was a similar build up of weaponry but in addition there was the Mirus Battery with a calibre of 30.5 cm and a range of 26 miles making this the largest gun in the Channel Islands.
This formidable array of weaponry, and the many concrete constructions that housed them, are described in detail by the Channel Islands Occupation Society and several types of these fortifications have been restored and are open to the public on certain dates - see their websites on the Links Page for more details.
You can buy the DVD from Amazon here
The Channel Islands at War: John Nettles stands next to a German naval observation tower in Jersey.