the exemptions. Legally, the Elbe below Hamburg was the same as the open sea and goods could be sent to and from Hamburg without hindrance. But if such duties were levied, Hamburg's entrepôt trade would be threatened. Hamburg protested vigorously against this infringement of ancient rights that guaranteed its free access to the open sea. But the Federal Council backed Bismarck's policy. On April 27, 1880 Versmann replaced Kirchenpauer as plenipotentiary to the Federal Council in Berlin. With prudence he raised reservations from Hamburg's point of view regarding the policy of Bismarck to annex Hamburg to the Customs Union. Submits to Chancellor’s policy By the middle of 1880, however, it was clear to all the insiders that an absolute opposition to Bismarck's plans would be pointless. On 29 June 1880, the Chamber of Commerce wrote to the Senate stating: “Hamburg has an opponent, who pursues his aims without recklessness, as long as he considers them to be the right one, an opponent whom we naturally cannot cope with, the opinion of which is not to be misjudged, whether it be in a political or commercial sense”. By a majority of 16 to 5, it called on the Senate to set up a programme for future negotiations with Prussia and demand a smaller free trade district, including facilities for Hamburg's export industry. The Senate was still largely against the Customs Union. The general public did not hear of the decision of the Chamber of Commerce, but rather the impression was expressed that the Chamber of Commerce still wanted to maintain the status of Hamburg as a free port city. With these double-tracked tactics, Senator Versmann and the Chamber of Commerce pursued the goal of strengthening the Hamburg position against Bismarck. The 1,730 name petition was used in this context. These tactics were essentially successful. In December 1880 and January 1881, Versmann, O’Swald and Hugo Roeloffs held "informational discussions" with the Prussian Superior Customs Inspector Klostermann and the Prussian Finance Minister Karl Hermann Bitter. In April 1881 they started actual negotiations in Berlin. Versmann, O'Swald and Dr. Friedrich Krüger (Hanseatic minister (envoy) to Berlin) negotiated the definitive conclusion of the agreement. On 25 May 1881 an agreement was signed between Prussian Finance Minister Bitter and the State Secretary of the imperial Treasury, on the one hand, Hamburg's Plenipotentiary Senators Versmann and O'Swald, and the envoy of the Hanseatic states in Berlin Dr.