Each year the population of Brielle commemorates that Den Briel was captured from the Spaniards by the Sea Beggars on 1 April, 1572. The celebration is a local public holiday, which attracts tens of thousands of visitors a year and in which hundreds of Brielleners take part.
The heart of the tradition is the performance of an open air play about the capture of Den Briel, by members of the 1 April Vereniging (1 April Society). The play is set at four locations in the inner town of Brielle: the Town Hall, the harbour, the Langepoort and at the 1 April monument at the Dijkstraat. In addition, atmospheric images of 1572 are being represented by several street groups and there are performances by the groups the Spaniards, the Sea Beggars, the Beggars’ Children and the Flagbearers. Around the celebration on 1 April, a number of side-activities take place like the Kalknacht (Chalk Night) in which funny phrases are written on the windows of houses and shops with a bucket of chalk and a brush in the early morning of 1 April. Besides there is a Beggars Meal for the elderly, and a traditional Crafts Market that fits into the atmospheric image is created on 1 April.