A union with Norway was established by force in 1814, but dissolved in 1905. A policy of armed neutrality was adopted in 1815. Sweden was neutral in the First World War, but continued to trade with the belligerent nations. This led to a blockade of Sweden by the Allies, in an attempt to reduce trade with Germany. An agreement was reached with the Allies in May 1918. Although neutral in the Second World War, Sweden was surrounded by German held territory and felt compelled to supply Germany with iron ore and allow free passage of German troops. Since 1945 Sweden has played a major role in the mediation of international conflicts, especially through the United Nations and its peacekeeping forces.