St. Lucia's flood

St. Lucia's flood (Sint-Luciavloed) was a storm tide that affected the Netherlands and Northern Germany on 13/14 December 1287 (OS), St. Lucia Day and the day after, killing approximately 50,000 to 80,000 people in one of the largest floods in recorded history. A low-pressure system combined with a high tide caused the North Sea to rise over seawalls and dykes, causing a large portion of the Netherlands and northern Germany to be flooded.

This disaster was similar to the North Sea flood of 1953, when an intense European windstorm coinciding with a high tide caused a huge storm surge. The St. Lucia flood had a major influence on the subsequent history of the Netherlands. As a result of this event, a large percentage of the country's population was killed.

The island of Griend in the current Waddenzee experienced serious destruction, with only ten houses left standing. After the flood, Harlingen, about 25 kilometres southeast of Griend and formerly landlocked, became a new major seaport of Friesland, a role it kept for seven centuries.

The only part of the current northwestern Netherlands, apart from the western Dunes area (the old Dutch heartland) and the Frisian Islands, that escaped annihilation was West-Friesland, since this area was already protected by a ringdike that mostly held and where not, could be repaired after the floods receded. Soon after the St. Lucia Day disaster, West-Frisia, now separated from the rest of Friesland by a strait of around 15 kilometres at its narrowest, was annexed by the county of Holland, expanding this county northwards. The flood also brought the Friso-Hollandic Wars, which had lasted about 200 years, to an end. Soon after this annexation, the West-Frisian cities of Hoorn and Enkhuizen began a rise to prominence that would last until the 17th century.