roughly the area now referred to as the Randstad), using traditional, static defence lines and fortified fixed positions. Winkelman did not have the illusion that the Dutch could push Hitler's armies back into Germany. Instead, the Dutch forces should simply slow the Germans down, win time and keep Fortress Holland in Dutch hands long enough to enable the Allies to join them. In practice, the three northern provinces (Drenthe, Groningen and Friesland) would remain largely undefended. State-of-the-art fortifications at the east end of the Afsluitdijk (the long dike connecting the Friesland and North Holland provinces) were expected to stop the German invasion and prevent the Germans from threatening Fortress Holland from the north. In the east of the country, the first line of resistance ran along the IJssel and Maas rivers. The main Dutch defence line, however, was in the very heart of the country and called the Grebbe Line, to be defended by the entire 2nd and 4th Army Corps. The Grebbe Line was to be defended until the bitter end, as the eastern front of Fortress Holland (the New Dutch Water Line, once the pride of the Dutch defence system was deemed obsolete and too close to major cities such as Utrecht and Amsterdam). The German invasion started on 10 May 1940 at 3:55 a.m. local time. Hitler's bold plan to drop paratroopers around The Hague, push into the city and capture the Dutch government, the Royal Family and the Supreme Army Command to force the Netherlands to its knees within 24 hours, ended in failure. In the east, the Germans crossed the Dutch borders with relative ease, but were halted near the main Dutch defences: the Grebbe Line and the Afsluitdijk fortifications. After one day of war, General Winkelman was relatively satisfied about the way his troops had reacted to the first German push. The only area where the situation was already critical was in the south: paratroopers had secured the Moerdijk bridges, south of Rotterdam and Dordrecht. Meanwhile, strong German infantry (supported by the 9th Panzer Division) had smashed through the so-called Peel-Raam Stelling and now marched rapidly through the southern province of North Brabant, threatening to establish contact with the bridge head at Moerdijk and to enter Fortress Holland from the south, effectively isolating the Netherlands from Belgium and France. An attempt, supported by French units, to recapture the Moerdijk bridges failed on 11 May.