Although it was generally thought that the negotiations then being conducted through the Palestine Conciliation Commission would rapidly lead to a general peace settlement, such hopes were soon frustrated. After the final breakdown of the commission's negotiations in 1951, the stresses on the armistice increased. As a result of terrorism it was becoming obvious that the agreements were wearing thin, and efforts were made by UN Secretary-General Dag Hammarskjold to arrest their deterioration, which was particularly marked in the case of the Egyptian and Syrian Agreements. In the Sinai Campaign of Oct.–Nov., 1956 Israel announced that because of Egyptian belligerency and persistent violations of the armistice, the Egyptian Agreement was no longer serving any useful purpose and withdrew from further participation in that Mixed Armistice Commission (M.A.C.) agreement.