The large number of windmills in Holland or the Netherlands, is due to the fact that they were needed to pump water into the canals off the rich, low-lying land reclaimed from the sea. Windmills are still used for this purpose today, but pumps worked by electricity are more usual.
There is and old Dutch saying, "God made the world, but the Dutch made Holland". They certainly did make a great part of their land by dragging it from the sea, and the battle to hold it never ceases. The name Netherlands (from the Dutch Nederland) means low land, and more than one third of Holland's land area of 12,530 square miles lies below sea level.
Along the coast are dunes of sand - nature's dykes - thrown up by normal tides. The Dutch plant them with marram grass, which holds the sand together with is long, strong, creeping roots. Behind the dunes the Dutch built three dykes of close-packed stone, clay and earth on wooden and concrete piles. The dyke nearest the sea is called a "waker". Behind it lies a "dreamer" and behind that again a "sleeper". Some of the dykes are 200-300 feet high and many have a road or some, a railway running along the top.
In 1770 the North Sea swept into the country and formed the bay called the Zuyder Zee (South Sea). In 1421, another high tide flowed in to form the Hollandse Diep (Dutch Deep). The great spring tide of 1953 (two feet higher than any previously recorded) smashed the waker dykes, overflowed the dreamers and drowned about 1,900 people. About 50,000 were forced to flee from their homes.
A famous Dutch story tells of a brave boy who stood for hours with his hand thrust into a hole in a dyke and so prevented the sea from rushing in and widening the breach in the wall.