Why did Hall want to contact Mr. H? Hall wanted Mr. H to intercept the telegram that von Bernstorff was going to send to the German ambassador in Mexico. Hall wanted Mr. H to report to Woodrow Wilson the findings of the Zimmermann telegram. Mr. H was a traitor and Hall wanted to find Mr. H to arrange an arrest. Mr. H knew the meaning of secret codes that the people in Room 40 could not decipher.