It was wrong to bomb Hiroshima and Nagasaki

But what if we could have ended the war without the A-Bomb? John Denson at Mises.org argues that we could have:

Japanese leaders, both military and civilian, including the Emperor, were willing to surrender in May of 1945 if the Emperor could remain in place and not be subjected to a war crimes trial after the war. This fact became known to President Truman as early as May of 1945.

Iā€™m no historian, and if anyone can refute the facts in this piece, please do ā€” because the article seems to make the clear argument that the atomic bomb was inexcusable.