Yoshinori was the head of the Sō clan from 1842 through 1862.
Black ships
Sō Tsushima-no-kami was a senior member of the Imperial Commission which was delegated the responsibility of meeting with Commodore Perry and his men on March 8, 1854. He sat next to Daigaku-no-kamiHayashi Akira in the conference meeting.
March 8, 1854 (Kaei 7, 10th day of the 2nd month): Commodore Perry returned to Edo Bay to force Japanese agreement to the Treaty of Kanagawa; and the chief Japanese negotiator was Daigaku-no kami Hayashi Akira, who was known to the Americans as "Prince Commissioner Hayashi".[1][2]
In the context of this unique negotiation with the Americans, Yoshinori's rank was considered secondary only to Hayashi. Perry construed his counterparts as an Imperial Commission consisting of five Commissioners with supporting staff and military support:
^Sewall, John S. (1905). The Logbook of the Captain's Clerk: Adventures in the China Seas, Bangor, Maine: Chas H. Glass & Co. [reprint by Chicago: R. R. Donnelly & Sons, 1995] ISBN0-548-20912-X. p.lxiv
^ abcHawks, Francis. (1856). Narrative of the Expedition of an American Squadron to the China Seas and Japan Performed in the Years 1852, 1853 and 1854 under the Command of Commodore M. C. Perry, United States Navy, Washington: A. O. P. Nicholson by order of Congress, 1856; originally published in Senate Executive Documents, No. 34 of 33rd Congress, 2nd Session. [reprinted by London:Trafalgar Square, 2005. ISBN1-84588-026-9 (paper) p. 549