Anglo-German Naval Agreement
The Anglo-German Naval Agreement (AGNA), was signed between United Kingdom and Germany in of June 18, 1935. Despite provisions in the Treaty of Versailles, the agreement negotiated by von Ribbentrop allowed Germany to increase the size of its Navy to one-third the size of the Royal Navy. At the same time, the United Kingdom agreed to withdraw its navy from the Baltic Sea completely, making Germany the dominant power in the Baltic. Adolf Hitler himself was privately ecstatic at the agreement, saying, "Great Britain has in fact renounced her naval influence in the Baltic, a bottle that we Germans can close. The English cannot exercise any control there. We are the masters of the Baltic." Even the Times of London reported that the "German Fleet will now be in unchallenged control of the Baltic. Every new unit added to the German fleet makes Sweden's (and the rest of the Baltic nations) position so much worse...Even before 1914 our position was better, as then the Russian and German fleets about balanced."
Impact
The Anglo-German Naval Agreement made it easier for the German navy to control a major portion of the sea traffic traveling in and out of the Baltic, including sea traffic traveling through the Gulf of Bothnia. It was from the Gulf of Bothnia and the Swedish port of Luleå where a majority of Germany's iron-ore imports were originating from. With 50 percent of Germany's iron-ore imports coming from Sweden, iron-ore was of major importance to Germany, especially for the German military's attempts at rebuilding its war arsenal. Grand Admiral Raeder, head of the German navy, said himself that it would be "utterly impossible to make war should the navy not be able to secure the supplies of iron-ore from Sweden."
Of course, at the time of the signing of the AGNA, Denmark had the capability of deciding what ships made their way into and out of the Baltic, but when the War began and Germany invaded Denmark and Norway (Operation Weserübung, April 9, 1940), it was Germany that gained complete control of the Baltic, since the United Kingdom had voluntarily withdrawn from Baltic waters. It was now truly a 'bottle' that the Germans were capable of closing. If the British naval withdrawal from the Baltic had not been included in the AGNA, and had the British navy continued to sail the waters of the Baltic, Germany's ability at securing the iron-ore shipping routes with Sweden in the Gulf of Bothnia in time of war may have been made more difficult and Germany's ability to initiate war may not have been possible with such a vital mineral as iron-ore cut off from the German mainland. The United Kingdom's superior navy may have been able to stave off a smaller German naval fleet, but in considering the power of the German Luftwaffe, Britain's ability at controlling the German navy might have been much more difficult than it would have appeared.
Germany's expanded power, as granted through the AGNA, posed a serious threat to the independence of nations that bordered on the Baltic, particularly Sweden and the Baltic states of Latvia, Lithuania and Estonia. It forced some of those nations to seriously reconsider their traditional policies up to that point.