His father, Friedrich Christian Georg Kapp (1798–1874), was a teacher and politician who took an active part in the revolutionary events in Westphalia in 1848.

Kapp received his Abitur from Gymnasium “Hammonense”, the same educational institution where his father held the position of principal.

Not only did they become close friends; Feuerbach's criticism of religion, which also strongly influenced Karl Marx, had a great impact on Kapp's attitude towards life as well.

Other acquaintances from his time as a student were Ludwig Bamberger (1823–1899), who would later become a banker, the author Berthold Auerbach (1812–1882) of Heidelberg and the poet Bettina von Arnim (1785–1859) of Berlin.

In Berlin, he was already working as a journalist for the utopian socialist magazine called "Westfälisches Dampfboot" (Westfalian Steamboat).

[3] His uncle, Christian Kapp, had become a member of the National Assembly in St. Paul’s Church over the intervening years.

Kapp worked as a political journalist in Frankfurt, but due to his involvement in the September Rebellion he had to flee to Brussels.

In 1846 Kapp had first thought about emigrating to the United States, but not until he arrived in Geneva did he make the final decision to leave.

Their aim was to correct overly enthusiastic reports on the U.S. being circulated in Germany and also to show the darker side of American reality.

Having become an American citizen in 1855, he was a lawyer until 1870 and worked as a foreign correspondent for the "Kölnische Zeitung", a newspaper in Cologne, Germany.

His loyalty towards Germany and his belief in a unified German state not only continued to dominate his own life but also the upbringing of his son Wolfgang.

In 1856, Kapp bought a house in Mansfield Square which was to become a popular location where the Germans of New York met to discuss literature and politics.

In 1855, he described the fairly poor living conditions of his fellow Germans in the Texan colony of the "Mainzer Adelsverein".

After a general amnesty had been granted to political opponents, Kapp returned to Germany in April 1870 at the urging of German friends.