Premise: The stubborn Americans came back again in 1853, with Commodore Matthew Perry bringing for the shogun (whom he mistook for the emperor) a polite but insistent letter from President Millard Fillmore and a promise to return the next year, with a bigger squadron, for a positive response.

Hypothesis: Commodore Matthew Perry mistook the shogun for the emperor when bringing a letter. 
Relation: entailment