He seems immediately to have thrown himself into other activities after coming into contact with Norwegian businessmen, possibly also participating in the high-level college of commercial advisors known as Kommercekollegiet of which a relative, Counsellor Christian Walter, was a member.

[4] Immediately after the 1750 death of the Danish merchant, Andreas Bjørn, Classen became involved in the annual delivery of munitions to the Berbers in Algiers.

He began by delivering 8,000 cannonballs, followed by gunpowder (500 centner), rope and timber, soon receiving a permanent contract to provide the delivery annually.

His international trading ties developed through his connection with the former Spanish ambassador in Copenhagen, Marqués de Puente Fuerte.

[4][5] In 1754, Classen unsuccessfully sought to establish a glassworks; the following year, he bought a ceramic kiln factory outside Copenhagen's Østerport.

[5] The same year, Frederik V entrusted Classen and another businessman, Just Fabritius, with land at Agatmølle, the point where the Arresø runs into Isefjorden, on which to develop a cannon and munitions factory.

[7] Fabritius provided the capital but it was Classen who became the active leader of the Frederiksværk operations, receiving the appointment of Commissioner General for War and Munitions with the title of chancellor.

Shortly afterwards, however, Saint-Germain was dismissed and in April 1768, an investigative committee was set up with Classen's opponent, Ditlev Reventlow (1712–1783) as chairman.

The committee found that the arrangements had all been set up in favour of Classen with the result that he had to give up the Kronborg rifle factory, which was transferred to Heinrich Carl von Schimmelmann, and pay 100,000 rigsdaler for Frederiksværk without any guarantee of contracts from the state.

The contract, which also specified an annual subsidy for operating the factory in addition to payments for the supplies, was renewed every year until Classen died.

He established the fishing communities of Sølager and Liseleje and developed large-scale plantations around Frederiksværk although his eagerness to persuade farmers to adopt better production methods does not appear to have led to meaningful results.

It was to be used "to educate good people to become the best in the State, to support and promote industriousness and diligence in the areas most necessary for the country's well-being, and to help to alleviate poverty and misery."