Willem van Loon joined his brother Anton van Loon along with six other members of the Achilles Krachtsportvereniging to form a tug-of-war team. Having won the Dutch trials at Utrecht, the squad also competed in Antwerpen, from which they returned with second place. This result was in doubt for some time, as the Official Results listed both the Netherlands and the US as winning second place. This confusion was ended in 1968, when Henk Janssen presented his silver medal and associated Olympic diploma.