Simplify the following text for a Grade 13 native English-speaking person.
Original: The following year , at the Convention of Kanagawa ( March 31 , 1854 ) , Perry returned with seven ships and forced the Shogun to sign the `` Treaty of Peace and Amity '' , establishing formal diplomatic relations between Japan and the United States .
Simplified: The following year 1854 ) , Perry returned with seven ships and forced the Shogun to sign the `` Treaty of Peace and Amity '' , establishing formal diplomatic relations between Japan and the United States .