In the end of February or the beginning of March 1945 Dutch workers start to undermine the dike around the polder under German command. The location is near the farm of Beetstra, in the dike with the IJsselmeer.
Deep holes are dug in the dike both at the bottom and at the top of the dike. In these holes explosives will be put. The work is going slowly, as none of the workers is motivated. In April the work comes to a complete stop.
On April 10 however, German officiers come and inspect the work. New workers are sought, and 25 or 50 people are taken from Schagen during a razzia to work on the digging. After a week the holes are deep enough, and explosives are installed. Unexploded bombs from British and American aircrafts are used. In each hole around 1000 kg explosives are put.
Reference
De polder onder water, het verslag van de onderwaterzetting van de Wieringermeerpolder in 1945, J. J. Bosman and P. C. Bosman, Free Media, 1995
Because of an employment project that was subsidised by the state, inhabitants from all over the country came to the Wieringermeer to help build an infrastructure.
On September 29 of the same year, the first inhabitants of the new land gave a memorial to the new mayor and aldermen.
On April 171945 the Germans bombed the dike and within two days the complete polder was all water again (see also inundation of the Wieringermeer).