The 'Grebbelinie' was a Dutch forward defence line of the 'Hollandsche Waterlinie', and was also based on inundation (1940).

The 'Grebbelinie' ran from the Grebbeberg in Rhenen to the north-west as far as the south shore of the IJsselmeer, and was initially created in 1745 as a line to protect the Netherlands from invasion from the east. If invasion was deemed imminent, parts of the area between Spakenburg and the Grebbeberg were to be flooded. Until World War II the 'Grebbelinie' was never used for this purpose. Throughout the 19^th century the 'Grebbelinie' was maintained as a defensive line, but then as attack came to seem increasingly improbable, the 'Grebbelinie' declined in importance and, largely for cost reasons, in 1926 a major part of the fortifications was decommissioned.

In 1939 the disused 'Grebbelinie' was once again fortified, in this instance again the possibility of a German attack on the Netherlands, but as a result of financial problems and a shortage of skilled labour (soldiers were used as the core of the labour force) the earthworks were not rebuilt to a high standard despite the fact that the Dutch defence plan of 1939 demanded that the 'Grebbelinie' become the Netherlands' forward defence line. In February 1940, however, the new Dutch commander-in-chief, General Henri Winkelman, decided to make the 'Grebbelinie' the main defensive feature in the central sector of the Dutch defences. The 'Grebbelinie' was deemed less useful than before as the Germans' modern field artillery could reach the main cities of Utrecht and Amsterdam from their positions opposing the defences.

Meanwhile, the Germans were aware of the layout and nature of the 'Grebbelinie' as, during the later part of the 1930s, German spies had visited the zoo at Rhenen and made use of its look-out tower to map the defences. When the Germans attacked in May 1940, the Dutch army managed to defend and hold the 'Grebbelinie' for three days, much to the surprise of the Germans, and the Battle of the Grebbeberg saw fierce fighting, during which 420 Dutch and approximately 250 German soldiers were killed.

During their occupation of the Netherlands, the Germans made use of the 'Grebbelinie' as the basis of their own 'Panther-Stellung' (ii). It was on 26 October 1944 that Generalfeldmarschall Walter Model, the commander of Heeresgruppe 'B', initiated the construction of the 'Panther-Stellung' (ii), though in a revised form as by this time it had become clear that the Allies would advance into the Netherlands not from the west but from the south. The Germans wanted to hold the area protected by the 'Grebbelinie' as it was from this that V-2 rocket attacks were being on London. The Germans were unwilling, of course, to lose their capacity to continue this missile bombardment and also wanted to prevent the Allies from reaching the IJsselmeer. The Germans therefore made some changes to the layout to cover against the perceived threat from the south, but from Veenendaal to Amersfoort the 'Panther-Stellung' (ii) had the same layout as the original 'Grebbelinie'.