Dr Gordon Barclay on the Nazi threat in ‘If Hitler Comes: Preparing for Invasion: Scotland 1940’

After the fall of Norway, Denmark, the Netherlands, Belgium and France between April and June 1940, all the countries directly east of the North Sea were in enemy hands. Britain crucially misunderstood German military thinking, believing that all German military operations were planned in great detail, far in advance. Therefore it seemed certain that, after the Low Countries and France, the next step would be an invasion of Britain, for which all the plans had already been made. The well-named “May Panic” saw hurried preparations begin across Britain to fight off an imminent invasion. The physical remains of these preparations can still be seen throughout Britain’s landscape today.

We now know that Hitler probably intended only to put pressure on Britain to negotiate, but in 1940 that was not how things seemed. Invasion seemed inevitable. It was also expected that the Germans would mount major diversionary attacks on Scotland, especially to neutralise the key naval bases at Scapa Flow and Rosyth, and to draw parts of the RAF northwards, away from the intended main invasion site in south-east England.

In the summer of May 1940, therefore, Britain was expecting an assault that had long been planned by a force that had smashed the armies of six countries in the previous nine months, using airborne troops and new forms of high-speed tank warfare with close support from the air.

One month later, the shattered remnants of Britain’s army returned from France leaving behind them their tanks, artillery, anti-tank guns and motor transport. As a consequence, the forces available to defend the island in the summer of 1940 had few heavy weapons with which to oppose a landing, and precious little transport to move to where the enemy might land. This largely immobile, lightly-armed force had to rely on the construction of fixed defences to try to stop the Germans overwhelming them using their speed and mobility. From June 1940 until the spring of the following year a major campaign of construction radically transformed the appearance of Britain’s landscape. What survives today is the tip of the iceberg – mostly structures too difficult to remove after the war.

In 1939 the important naval bases at Scapa Flow in Orkney, Invergordon, and in the Forth, and the port and shipbuilding centre in the Clyde still retained some of their First World War coastal defence guns. Further defences were hurriedly built around the major ports that would be needed by an invading force to bring in fuel, ammunition and reinforcements: Wick, Peterhead, Aberdeen, Montrose and Dundee were defended by batteries of six-inch guns, and four-inch naval guns were placed to defend vulnerable beaches on the east coast.

The places seen as most at risk were where a port lay close to an aerodrome and a beach, where airborne and seaborne troops might land, and then seize the port. Any open space within three to five miles of a key aerodrome or port – golf- courses, fields, beaches, lochs – was obstructed by ditches or tall wooden posts to stop gliders, aircraft and even seaplanes from landing. The pattern of beach posts can still be seen on the sands at Burntisland, and west of Dunbar, where they have been cut down to a foot or two in height; but on the coast between Nairn and Findhorn, hundreds of these poles still stand to their full height.

To deal with a possible assault on the beaches, miles of concrete cubes were built, covered by dozens of pillboxes strung along the barriers. Those built near towns, and especially those on holiday beaches, were removed immediately after the war but hundreds are still visible or are buried beneath the sand. Within months many of the cubes had been toppled by the sea or buried by sand, and from late 1941 until the spring of 1942 additional barriers of scaffolding poles were planned. Most of the scaffolding poles, however, were left to rust in piles on the beaches. The world had moved on and the commanders of the troops who were supposed to put them up felt that their mens’ time would be better spent training for mobile warfare. Indeed, tests of the effectiveness of all these barriers showed that they would only have held up a tank for two minutes or so.

Further defences were built inland, to bar the progress of any fast-moving German tank columns that might have broken through the beach defences. These stop-lines used natural barriers wherever possible but, where there were none, lines of anti-tank ditches were built across the countryside. The most impressive of these was the “Scottish Command Line”, which ran in the form of a double ditch across Fife from Dysart to Newburgh, with over 70 roadblocks and 13 pillboxes. The northern part of the Command Line resumed at Kinfauns, east of Perth, and ran to Murthly, near Dunkeld. The Command Line was intended to stop any invading force that had landed on the vulnerable beaches of east Fife or Angus from moving south-west towards Scotland’s industrial heartland.

Two other stop-lines were built in 1940 on the Scottish mainland (although others were planned, and lines were also built in Orkney and Shetland). The first was the Cowie Line, running westwards from the coastal town of Stonehaven, intended to prevent any invader that had landed on the beaches of Aberdeenshire moving south. It relied on the banks of the Cowie Water to act as an anti-tank barrier and for several miles where the bank was not high it was raised. The second was at Bonar Bridge, where the broad sea inlet of the Kyles of Sutherland cuts deep into the Scottish mainland; in 1940 all traffic had to cross at Bonar Bridge. Here, over 20 pillboxes, the greatest local concentration in Scotland, were built to bar the crossing, should the Germans capture Caithness and try to move south.

In May and June 1940 there were what seemed like a very impressive number of army personnel based in Scotland – 181,000 – but of these, only nine battalions of infantry (about 7,000 men) were considered by the Commander of Scottish Command, General Carrington, actually to be effective as a counter-attacking force. The rest were “static” troops, manning anti-aircraft guns, searchlights or in support units, with few weapons, little infantry training and no transport. In October 1940, however, the forces defending Scotland received a major reinforcement – about 18,000 Polish soldiers, who had been evacuated from France in June. With the then commonplace British attitude to foreigners, Carrington at first wanted to use the Polish units merely to cut timber, but their value as well-trained, experienced and highly motivated troops soon became clear. They significantly improved the beach defences they had inherited in Angus and Fife, built far more effective pillboxes, and positioned them much better than their British colleagues had done. One British Home Defence infantry battalion revealingly described the Poles as “too keen”, perhaps reflecting the unfortunate British “amateur” disdain for the professional. The Home Guard had been formed in the spring of 1940, but during the main invasion scare of that summer it was still poorly armed and trained; it became a very effective force in time, but only after any real threat of invasion had passed, in the autumn of 1941.

The anti-invasion defences that still mark our landscape reflect a herculean effort made in the months after May 1940, until any threat of German invasion was over. Britain was preparing to rebuff an enemy whose style of warfare our forces were not trained, nor, after Dunkirk, equipped to deal with. But even before the defences were completed, they had become obsolete, as the British Army began to train for the mobile style of warfare needed to defeat Nazi Germany. As Stephen Bungay has written, in his splendid account of the Battle of Britain, The Most Dangerous Enemy: “If Britain had given up in 1940, the war could have had one of two possible outcomes: Nazi or Soviet domination of Europe.” The built defences that survive from that limited period of time are, literally, a concrete memorial to Britain’s gritty determination to resist invasion at a critical turning point in world history.

• Dr Gordon Barclay worked as a director of excavations and then as principal inspector at Historic Scotland, retiring as head of policy at the end of 2009.

• Scotsman readers can purchase If Hitler Comes: Preparing for Invasion: Scotland 1940 by Gordon Barclay for the special price of £17 (including p&p in the UK) by calling 0845 370 0067 (office hours) and quoting ref SM413.