The Dutch Waterline was a Dutch defense line on the basis of Inundierung. In the defense case, the land could be flooded as 40 inches high.
Old Dutch Waterline
After allowing the Inundierung 1589 and 1629 tried on a smaller scale, a tract of land was in 1672, the so-called Rampjaar, hurriedly put under water to stop the French troops in the French-Dutch War, before they would conquer Holland. The line ran from the Zuiderzee to the Biesbosch of Muiden about Woerden and Goejanverwellesluis to Gorinchem. The city of Utrecht fell outside this line, because it was already conquered at this time by the French.
New Dutch Waterline
1815 Krayenhoff recommended the construction of the New Dutch Waterline or Utrecht line. Construction began in 1816 and lasted, with an interruption in 1824 to 1839 to the 1860. As part of the defenses, which were called Fortress Holland further expansion works have been made to 1885 later. However, the forts were with the invention of the explosive grenade in 1880 no longer appropriate, since their attachment in case of war would not be sufficient.
The line was partly due east of the Old Dutch Waterline, so that Utrecht was within the line. In those places where the Inundierungen were intersected by roads, dikes, or railroads, forts were built.
The New Dutch Waterline was occupied at the outbreak of the Franco-German War in 1870 and during the First World War. Even in 1940, the line was not put into use. One but decided at the last moment, the defense continues to lead in the east Grebbe line where you stand up to a few days. When they finally did retire to the water line is, this was bombed already broken at Dordrecht and Rotterdam.