The primary role of the Netherlands as a member of NATO was to help in defense of West Europe, primarily West Germany and Norway, in case of war with the Warsaw Pact. Their main contribution to this was the I Netherlands Corps stationed in West Germany as part of NORTHAG (Northern Army Group), and their marines.
The Dutch marines, officially Korps Mariniers (KM), were mostly tasked to help defend Norway along with British and US marines. Other KM units were to protect the Netherlands Antilles, and a few to defend Naval Bases in the Netherlands itself. Almost all of the units fighting in Germany would be from the army, Koninklijke Landmacht (KL).
The I Netherlands Corps in peacetime was mostly stationed in the Netherlands, with only a small force stationed in West Germany; one tank brigade containing two tank battalions and one mechanized battalion and then a reconnaissance and engineer battalion, all of which were forward deployed as part of the 4th Division.
There were a few other small support units there as well, such as a platoon from the 41 Military Police Squadron and the 41 Anti Aircraft Battery, but they were attached to the 41 Pantserbrigade.
In the event of war, in a favorable situation the Dutch would have three full divisions deployed in West Germany, the 1st, 4th, and 5th:
1e Divisie "7 December" (1 Div "7 Dec") - Would deploy to the southern sector north of Celle, near Uelzen, directly west of the Elbe-Seitenkanal.
4e Divisie (4 Div) - Would deploy to the northern sector just south of Hamburg, near Lüneburg, directly west of the Elbe-Seitenkanal.
5e Divisie (5 Div) - Mobilization Unit - Corps Reserve - Would be deployed to the corps rear area east of the Weser river.
The 1st Division "7 December", and 4th Division would hold the main front line while the 5th Division would act as a corps reserve, used as a counterattack force as needed. Several other units would also be included such as the 101 Infantry Brigade which would be in charge of securing the corps' rear area.
The problem with this plan is that it relies heavily on the assumption that they would have had the time to prepare before war. It would take at least 48 hours for the 1st and 4th Divisions to get everything ready and arrive in position in Germany, and even longer for the 5th Division which was almost completely unmanned and needed to mobilise its forces first. At this time the Dutch Army was mostly conscripts, and many of its units were not to be manned until needed. This meant that before it could rush off to battle it needed to gather its manpower first by calling up soldiers who had recently been discharged from the army after serving their time.
Because of this, there was great fear that the Dutch would not be able to defend the area given to them. The Dutch Sector was of large importance due to the fact that it was NORTHAG's left flank, and also because it was also the left flank of AFCENT (Allied Forces Central Europe). In order to maintain contact with BALTAP (Allied Forces Baltic Approaches) in northern Germany and Denmark, I Netherlands Corps had to hold.
By the 80s it became clear that a warning might not come, and if one did it might be on very short notice - not the 3 or so days needed for the Dutch to get ready. The Warsaw Pact had become much faster at deploying than it had been in the 60s and early 70s when this strategy was originally adopted, and many believed that a surprise attack was a great possibility. If the Pact did manage a successful surprise attack the Dutch sector would be seriously undefended. In order to prevent this, in the event of war the West German 3rd Armored Division and the forward deployed units of the US 2nd Armored Division would help the 41 Pantserbrigade hold the area until the 1st and 4th Divisions were in place.
The Warsaw Pact planned to throw a massive force at the Dutch, including the Polish 2nd Army and East German 5th Army as well as elements of the Soviet 2nd Guards Tank Army.
With a majority of its army in Germany and its marines in Norway, the Dutch did have some units at home, such as the 302 and 304 Infantry Brigades, and many Security Infantry Companies spread across the country. Their main role would have been to protect against airborne attacks and acts of sabotage.