[4][self-published source] He belonged to the co-founders and was one of the first members of the Grand Old Party, and was a close confidant of Abraham Lincoln and his wife Mary Todd, and had an essential role in his nomination and election for president in 1860.

[1][5] On Christmas Eve 1830 in Munich, Koerner was involved in a somewhat drunken snowball fight that led to a confrontation with the Gendarmerie of that city in royal Bavaria where an officer was knocked down and wounded.

Because of his participation in these so-called "Christmas riots," he was taken into custody for four months, later recalling that during the time of his captivity he learned more about the law than during the whole of his two-years of study at the University of Jena.

The German Confederation's legation of sovereigns, the Bundestag (officially called the Bundesversammlung, Federal Assembly), was located in the Palais Thurn und Taxis in the center of Frankfurt, Koerner's native city.

During the Frankfurter Wachensturm in 1833, a failed attempt by students to start a revolution in all states of the German Confederation, Koerner was injured and, to avoid being prosecuted by the authorities and held captive for high treason which would threaten capital punishment, he escaped in female dress to France.

The Free City of Frankfurt was occupied by federal troops from Austria and Prussia which meant a de facto total loss of its independence.

[6][9] On 1 May 1833, Koerner boarded a ship in Le Havre sailing to North America with a group of emigrants headed by the patriarch of the Engelmann family, whose son Theodor was an old friend of his from college.

On the passage he became engaged to his future wife Sophie, a daughter of Engelmann's who was born in Imsbach in the Palatinate (Pfalz), a historic region of Germany.

(Demonstrating the sincerity and earnestness of Koerner's attitude toward the abolition of slavery, the 50th anniversary edition of the "Belleviller Zeitung" printed this example from "those memorable days of the anti-slavery movement: A large crowd was gathered in great excitement in Belleville's public square.

Although Koerner, the Envoy Extraordinary and Minister Plenipotentiary of the United States of America (his precise titles as ambassador) managed to accomplish this objective, he was discontented in Spain and asked the president several times for a replacement.

An important reason prompting his request was that the stipend for his ambassadorship did not nearly cover the huge financial obligations expected of him at the Spanish court.

[11] In 1874, Koerner's wife Sophia, together with Henry Raab (1837–1901), a German immigrant (1854) from Wetzlar, a librarian in Belleville and later a well-known educator,[10] established, with others, one of the first kindergartens.

She became the first president of the Belleville Kindergarten Association which received $2,100 (~$51,047 in 2023) in contributions from 70 shareholders and, supported by 150 other women, one year later was serving 201 pupils taught by three educators.

[10] Although he had never pursued agriculture as a profession, he is counted among the group of Latin farmers, which was a half-satirical, half-respectful designation for people like him, German immigrants in the United States who had received an advanced academic education.