He obtained his PhD at the University of Groningen in 1967 with a dissertation titled: "Wijster, a native village beyond the imperial frontier 150-425 AD.
"[1] He was named part-time professor (Dutch: buitengewoon hoogleraar) of prehistory and protohistory of Northwestern Europe at the Vrije Universiteit Amsterdam in 1968.
[1] Van Es became director of the Rijksdienst voor het Oudheidkundig Bodemonderzoek (ROB) in 1965 and remained in charge until 1988.
[1][2] When van Es took over as director from his predecessor Glazema he applied for more staff and financial funds to avoid having to throw away findings without even having done a proper analysis.
Van Es also performed excavations in grave fields and settlements in the province dating back to the Middle Ages.