Historical Notes: The two main characters used in this novel that were not fictitious were John Ericsson and Samuel Dana Greene. Part III until the end of the novel was a completely alternate history, although much of the research came from many verified sources, including a great debt of gratitude to Professor Jared Diamond, author of the best-selling non-fiction works, Guns, Germs and Steel and Collapse: How Societies Choose to Fail or Succeed.

Later, Ericsson worked with torpedo inventions, in particular the Destroyer torpedo boat, and in the book Contributions to the Centennial Exhibition he presents the so- called "sun engines", using solar power as propellant for a "hot air engine". Once again bitter and plagued by economic difficulties, his invention of the solar engine would not have practical applications for another 100 years.

Although none of his inventions created any large industries, he is regarded as one of the most influential mechanical engineers ever to live. After his passing in 1889 his remains were brought from the United States to Stockholm by USS Baltimore and to the final resting place at Filipstad, in his Varmland.

On December 11, 1884, while at the Navy Yard, Samuel Dana Greene committed suicide by shooting himself with a .38 caliber revolver. The Concord [New Hampshire] Evening Monitor reported on December 12 that "He had been observed to act strangely for some time, and had been watched for fear that he might take his own life." His suicide was attributed by some to criticisms of his actions on the Monitor after Worden was wounded. Recent articles in the press had brought old rumors to light and it was believed that Greene had not been able to cope with the resulting publicity. There is also some indication that he was in poor health at the time of his suicide.