A direct submarine telegraph link between Japan and the US was opened in 1906 (Meiji 39). It was a epoch-making event, as it was the first international telecommunication line that did not depend on the Daihoku Telegraph Company. The cable lengths used in the Japan-US submarine link were 646 nautical miles between Japan proper and Chichijima Island, and approximately 930 nautical miles between Chichijima Island and Guam. The laying of the cable between Kawasaki (Japan proper) and Chichijima Island was started in May 1905 (Meiji 38) without waiting for the official agreement between Japan and the US. Laying was completed in June the following year. Before public use of the Japan-US submarine link started (on the 26th), congratulatory telegrams were exchanged in June 1906 between the Emperor and President Roosevelt who mediated the peace in the Russo-Japanese war.