He served as the second Secretary-General of the Department of Public Information and the Arts [nl], which had been established by the civilian regime installed in the Netherlands by Nazi Germany during the occupation.

[1] He advanced the party's interests through journalism, being part of the team that prepared the first issue of its weekly periodical Volk en Vaderland (January 1943) and remaining on its board of editors through 1938.

[4] After a falling out with NSB chairman Anton Mussert, Secretary General of the Department of Public Information and the Arts [nl] Tobie Goedewaagen resigned from his position on 28 January 1943.

[6] Reydon was named his successor, thereby becoming secretary general as well as the president of the Nazi-established Nederlandsche Kultuurkamer (Chamber of Dutch Culture)[4] – an institution that was tasked with nazifying art by regulating its production and distribution.

[1] In a speech, Cornelis van Geelkerken, the deputy chairman of the NSB, claimed that Wilhelmina was shot and killed by an intruder, who then waited fifteen minutes and attacked Hermannus as he entered the house.

[1] Two days later, a hall at the Department of Public Information and the Arts' headquarters at the Prinsessegracht in the Hague was converted into a funeral parlour, with Reydon's body displayed to NSB members and staff.

On 28 August, a funeral for Reydon was held, attended by numerous high-ranking members of the Nazi regime, including Mussert, reichskommissar Arthur Seyss-Inquart, SS representative Hanns Albin Rauter, and propagandist Wilhelm Ritterbusch.

[8] In retaliation for the attack on the Reydons, as well as the assassination of General Hendrik Seyffardt on 5 February, the Nazi regime began killing suspected members of the Dutch resistance.