What is John holding in his right hand?
The treaty of the Union of Utrecht!
If you look closely, you can see a piece of paper with the numbers 1579 written near his right hand. 1579 is the year in which the Union of Utrecht came about.
John of Nassau signed the treaty
The Union of Utrecht was signed on January 23, 1579, in the Kapittel hall of the Dom Church. Nowadays it is the auditorium of the University Hall. To commemorate this moment, it was re-enacted 400 years later in 1979. (see photo).
Collaboration between the northern provinces of the Netherlands
The Union of Utrecht was a treaty that united the northern provinces (the orange areas on the map). Together, they fought the Spanish. In the end, this collaboration resulted in the Republic of the Seven United Netherlands.
The pride of Utrecht
Many places in the city of Utrecht still refer to the Union of Utrecht. For instance, here you see the signing of the treaty depicted on the Oudegracht. This artwork can be found on the canal side, under the lamp post in front of Oudegracht 158 (Winkel van Sinkel).
Even the mayor got dressed up!
This is Henk Vonhoff dressed up as John of Nassau for the opening of the renovated Dom Square. He was the mayor of Utrecht between 1974 and 1980.