The German guarantee for Belgium

On 13 October 1937 the Reich government handed the Belgian government in Berlin a unilateral declaration. In it Germany acknowledged that the inviolability and integrity of Belgium were of common interest to the Western powers, and confirmed that it would “in no circumstances” impair them and would at all times respect Belgian territory. The only exception, it was noted, “went without saying”: if Belgium, in an armed conflict in which Germany was involved, were to take part in military action against it. The Reich also declared that, like Britain and France, it was ready to come to Belgium’s aid should Belgium be attacked. The Belgian government replied the same day that it received the declaration “with great satisfaction” and thanked Berlin warmly for it. The declaration is usually described as a guarantee of Belgian sovereignty on condition that Belgium did not take part in hostilities against Germany. That description fits the document; it need only be added that this was not a treaty but a unilateral undertaking of which Belgium took note. Less than three years later, on 10 May 1940, the Wehrmacht marched into Belgium without a declaration of war.

From imposed neutrality to alliance with France

Belgium knew the value of such assurances. Its perpetual neutrality had been guaranteed by the powers, Prussia among them, in the Treaty of London of 1839. In August 1914 Germany demanded passage for its armies and, after King Albert I refused, occupied almost the whole country. Chancellor Theobald von Bethmann Hollweg then called the treaty a “scrap of paper”, and the violation of Belgian neutrality became Britain’s reason for entering the war.

After the war Belgium concluded that neutrality had not protected it. The Treaty of Versailles abolished the status of 1839, and in September 1920 Belgium signed a military agreement with France. Belgian troops took part in the occupation of the Rhineland and in the occupation of the Ruhr. At Locarno in 1925 Germany recognised its border with Belgium, and Britain and Italy guaranteed it. Belgian security thus rested on two pillars: the alliance with France and the demilitarised Rhineland, which kept the German army away from the border.

“A policy exclusively and wholly Belgian”

Both pillars were shaken in 1936. The alliance with France had long been a thorn in the side of the Flemish movement, which feared that it would drag the country into someone else’s war, and in the elections of May 1936 Léon Degrelle’s right-wing Rex party scored a success. In the spring of 1936 Belgium dissolved the 1920 military agreement with France, keeping only staff contacts. Then came the remilitarisation of the Rhineland on 7 March. German garrisons once again stood on the Belgian border, and the inaction of France and Britain showed the Belgians what the Locarno guarantees were worth.

On 14 October 1936 King Leopold III addressed the Council of Ministers, which was debating a bill to lengthen military service. He said that the remilitarisation of the Rhineland and the end of Locarno had put Belgium back almost where it had been before 1914, and that alliances, even purely defensive ones, could not protect it, because the allies’ help would arrive only after the country had been destroyed. Belgium was to pursue “a policy exclusively and wholly Belgian”, which would keep it out of its neighbours’ quarrels, and at the same time to arm itself so that it could defend itself against any invader. With the consent of Paul van Zeeland’s government the speech was published. The Foreign Minister, Paul-Henri Spaak, called the new course a “policy of independence”. Paris received it with bitterness, Berlin with satisfaction.

Release from Locarno and Berlin’s response

Belgium wanted guarantees without obligations. On 24 April 1937 Britain and France, in a joint declaration, released it from its obligations towards them under Locarno, while themselves maintaining their promise of help in the event of aggression. Belgium for its part announced that it would defend its borders with all its strength and would not allow its territory to be used as a route for aggression against another state.

Germany could not be left behind. As early as 30 January 1937 Adolf Hitler had declared in the Reichstag that the Reich was ready to recognise and guarantee Belgium and the Netherlands as inviolable neutral territories. The declaration of 13 October 1937, signed by the Foreign Minister, Konstantin von Neurath, fulfilled that announcement. In it the Reich government took note of Belgium’s policy of independence and of the Anglo-French declaration of April, and treated Belgium as a state that decided on its own defence. In this way Belgium, without binding itself to anyone, had assurances from both sides.

For Hitler it was a cheap and advantageous gesture. It confirmed Belgium’s departure from the French camp and closed to France the most convenient route to the Ruhr. Belgian neutrality meant that the French army could not enter Belgium before a German attack, and that the general staffs of the two countries could not openly prepare a joint defence. Between the Maginot Line, which ended at the Belgian border, and the sea there remained a gap that the French could close only by marching deep into Belgium at the last moment. Three weeks after the declaration, on 5 November 1937, Hitler spoke to his commanders at the Reich Chancellery of a war that was to win Germany “living space”.

A broken promise

As war approached, Germany repeated its assurances. On 26 August 1939, a few days before the attack on Poland, the Reich’s envoys in Brussels and The Hague assured both governments that Germany would respect their neutrality. Hitler repeated this in the Reichstag on 6 October 1939. Three days later, on 9 October, he ordered preparations for an offensive in the west through Belgium, the Netherlands and Luxembourg. On 10 January 1940 a German aircraft carrying an officer with parts of the plans for this offensive made a forced landing near Mechelen-sur-Meuse, but even the Mechelen incident did not persuade Belgium to enter into an open alliance with France and Britain.

On 10 May 1940 Germany attacked Belgium, the Netherlands and Luxembourg. In a memorandum handed over that day it accused both states of not having been truly neutral and of having secretly cooperated with the Allies, which was supposed to release the Reich from its word. Paratroopers and glider-borne sappers captured Fort Eben-Emael, regarded as the strongest fortress in Europe. The French and British armies, in accordance with the Dyle Plan, entered Belgium only after the German attack and fell into a trap when the main German blow came through the Ardennes. After eighteen days of fighting, on 28 May 1940, Leopold III capitulated without asking the government’s consent, and the dispute over his conduct divided Belgians for years.

Significance

The declaration of 13 October 1937 shows well how Hitler’s diplomacy worked in the 1930s. Assurances of peace and of the inviolability of borders, handed out in speeches and notes, were meant to reassure neighbours, break up coalitions and cut potential victims off from their allies. Belgium, which hoped to protect itself through neutrality, in practice made it easier for Germany to prepare the war in the west, because it made joint defence planning impossible. Like the declaration with Poland of 1934, the German guarantee for Belgium was worth exactly as much as Hitler considered expedient at any given moment. In May 1940 its violation opened the way to the defeat of France.