Overrunning dikes, it shattered the coastline and caused thousands of deaths (8,000 to 15,000 people drowned) and catastrophic material damage.

Supported by a Danish expeditionary fleet, they succeeded in repulsing first an imperial army and later the duke's men, but were eventually defeated in 1629.

[1] Several storm floods are reported by the chronicles during the years prior to 1634; the fact that the dikes did not hold even during summer provides evidence for their insufficient maintenance.

The most comprehensive report is preserved from Dutch hydraulic engineer Jan Leeghwater who was tasked with land reclamation in a part of the Dagebüll bay.

On a strong door on the western side of the building the lock bars sprang out of the posts due to the sea waves, so that the water doused the [hearth] fire and ran into the corridors and over my knee boots, about 13 feet higher than the May floods of the old land.

I have also ridden there along the beach and have seen wondrous things, many different dead beasts, beams of houses, smashed wagons and an awful lot of wood, straw and stubbles.

And I have also seen many a human body who had drowned.The witness Peter Sax from Koldenbüttel described the scenario as follows:[5] ...at six o'clock at night the Lord God began to fulminate with wind and rain from the east; at seven He turned the wind to the southwest and let it blow so strong that hardly any man could walk or stand; at eight and nine all dikes were already smitten...

The Lord God [sent] thunder, rain, hail lightning and such a powerful wind that the Earth's foundation was shaken... at ten o'clock everything was over.In combination with half a spring tide, the wind was pushing the water against the coastline with such a force that the first dike broke in the Stintebüll parish on Strand island at 10 p.m. About two hours past midnight the water had reached its peak level.

[citation needed] The water rose so high that not only were the dikes destroyed but also houses in the shallow marshlands and even those on artificial dwelling hills were flooded.

In this night the dikes broke at several hundred locations along the North Sea coastline of Schleswig-Holstein and southwestern Jutland.

Numerous people were killed in the coastal marshlands and victims were recorded even in settlements in the back-country like Bargum, Breklum, Almdorf or Bohmstedt.

[7] The Burchardi flood had especially severe consequences for Strand island where large parts of the land were lying below sea level.

This meant that a lot of arable land which had still been worked on directly after the flood had to be abandoned in later times because it could not be kept against the intruding sea.

M. Löbedanz, the preacher of Gaikebüll, describes the situation on Nordstrand after the flood:[10] More than half of the dwelling places have been wasted and the houses have been washed away.

The number of victims who spoke the idiom was too high and moreover many islanders moved their homes to the mainland or the higher hallig Nordstrandischmoor – against the order of Duke Frederick III.

Finally the Duke enforced the Frisian law of De nich will dieken, de mutt wieken (Low German:"Who does not want to build a dike, shall lose ground"), expropriated the locals and attracted foreign settlers with a charter that promised land and considerable privileges to investors in dikes, like the sovereignty of policing and justice.

The evangelical enthusiast and poet Anna Ovena Hoyer interpreted the Burchardi Flood as the beginning of the apocalypse.