What role did Emperor Hirohito play in the surrender of Japan?

In September 1945, following the atomic bombings of Hiroshima and Nagasaki, Hirohito broke the precedent of imperial silence and announced the nation's unconditional surrender to the Allied Forces.

The correct answer to this open question is the following.

The central idea of this document is that Charles Sumner, a Congressmen from Massachusetts, objected to the Mexican American War.

The evidence from the text is that Sumner writes that after Mexico won its independence from Spain, many Americans started to emigrate to the Texas region with their slaves,  defying the Mexican law that stated that in Mexico, slavery was forbidden.

According to this document, the United States was not justified in going to war with Mexico. Charles Sumner writes that more people arrived in the Texas territory and the Press motivate people to occupy the lonely territory, denying the Mexican legislation. So in his perspective, Sumner says that these actions were not appropriate and that Mexico could have charged these Americans with robbery. And he also stated that slavery was against the principle of freedom in the United States.

AS we know, finally the United States waged war against México in the Mexican-American War. The US won the war and Mexico lost the following territories: Nevada, California, Utah. Arizona, part of New Mexico, and Wyoming.