The Grimm–Hoffmann affair was a short-lived scandal that seriously brought into question Switzerland's neutrality during World War I. Robert Grimm, a socialist politician, travelled to Russia as an activist to negotiate a separate peace between Russia and Germany, in order to end the war on the Eastern Front in the interests of socialism. When the Allies found out about the proposed peace deal he had to return home. Arthur Hoffmann, the Swiss Federal Councillor who had supported Grimm, had to resign.
The Allies insisted that this situation be maintained in order to keep German troops busy on both sides rather than all the German forces focusing on one single front.
Then, Tsar Nicholas II of Russia was overthrown in the 1917 February Revolution and Alexander Kerensky took power. Lenin, the leader of the Russian Bolsheviks, was living in exile in Switzerland. Unlike Kerensky, Lenin was willing to make peace with Germany, whatever the cost and regardless of the views of Russia's Western allies. It was for this reason that the Germans assisted in Lenin's return to Russia.
Grimm goes to Russia
Robert Grimm was a socialist member of the Swiss National Council and the organiser of the Zimmerwald Conference. In the spring of 1917 he went to Petrograd. When a telegram sent between Grimm and Arthur Hoffmann, the Swiss Federal Councillor responsible for the Political Department and head of the Swiss foreign ministry, stating that a separate peace could be possible, was made public, there was outrage from the Western powers.
Grimm was expelled from Russia.