and a defence co-operation agreement with Norway. Hammarskjöld's refusal to negotiate trade agreements with the Entente countries resulted in unrest in Sweden. Hammarskjöld's government also became weakened around this time when the "Luxburg Affair", involving Swedish facilities being used to transmit secret messages targeting allied shipping for the Germans, became known. Angered by Hammarskjöld's rejection of trade with the Entente, Hammarskjöld's allies in the Swedish parliament rebelled against him. In early 1917, a combination of protests over food shortages and the failure of the Riksdag to approve increased defence spending, forced Hammarskjöld to resign. King Gustaf called on the conservative Ernst Trygger to form a government, however he lacked the necessary support in the Riksdag to do so, so he was instead replaced by Carl Swartz in March 1917. The replacement of Hammarskjöld by Swartz did not prevent further disturbances, which were inflamed by heavy-handed policing of so-called "hunger marches". Nor did the food situation in Sweden improve, as rationing was extended to include potatoes. In May 1917 disturbances hit the island of Seskarö in northern Sweden, where fighting broke out between the local population and the military in which the police had to intervene. The island was only pacified after a shipment of food reached the island and a number of local men were jailed. The largest disturbance occurred on 5 June 1917, when 20,000 people assembled near the Riksdag in Stockholm to hear the response of Carl Swartz to a request from Hjalmar Branting to introduce universal suffrage and constitutional reform, and were dispersed by mounted police. Swartz served as Swedish prime minister for only seven months before being forced from power after the Swedish elections of 1917 and replaced by the liberal government of Nils Edén. Following Edén's election disturbances subsided as the social-democrats stopped supporting them, though demands for reforms, including an 8-hour day and improved living conditions, continued. However, it was not until 29 May 1918 that the British blockade of trade with Sweden was completely lifted. The sinking of Swedish ships by German U-boats continued until the end of the war and were eventually to total 280 ships with a loss of 800 lives. Swedish occupation of the Åland Islands During late 1917, as the German army advanced on the Russian capital of St. Petersburg, Richard von Kühlmann, the new German Secretary of State for Foreign Affairs, renewed Germany's offer to champion Swedish sovereignty