 For 22 years, from 1857 to 1877, Pieterszen served as "agent-général" of the committee of evangelisation ("Comitée Synodal d'Evangelisation"); from 1860 to 1867 as editor of "L'Union", the official paper of the Belgian Protestants, too - but this additional task proved to be too much for him.Pieterszen was among the six founders and governors of the Evangelical College ("Vlaamsche Opleidingsschool") in Laeken, near Brussels, established in 1875 under the direction by N. de Jonge.16–17 July 1878, Ds.