This was a Dutch programme to expel ethnic Germans from the Netherlands (1946/48).
'Black Tulip' was initially proposed in 1945, just after the end of World War II, by Hans Kolfschoten, the Dutch justice minister, for the deportation of all Germans from the Netherlands. The undertaking lasted from 1946 to 1948, and witnessed the expulsion of 3,691 Germans, constituting some 15% of the German residents in the Netherlands.
After World War II, the Netherlands was a ruined nation with its pre-war trade links with Germany and the Netherlands East Indies n on-existent. As a result of the importance of trade with Germany, the proposed demand for compensation of 25 billion guilders (10 times the actual damage) was dropped, but there remained significant anti-German resentment. This saw the arrest of many people, most especially collaborators of the Dutch Nazi party. At the same time the 25,000 Germans living in the Netherlands were branded as 'hostile subjects'. These were earmarked for deportation in three groups in reverse order of entry. The first who had to leave were those who came after the start of World War I (most of them factory workers), then those who came after 1932 (including political refugees, some of them Jews), and then the remainder (many of them economic refugees from the 1920s).
'Zwarte Tulp' began on 11 September 1946 in Amsterdam, where Germans and their families were taken from their homes in the middle of the night, given one hour to collect 110 lb (50 kg) of baggage and allowed to take 100 guilders; the rest of their possessions were seized by the state. The deportees were taken to internment camps near the German border, the largest of them at MariŽnbosch near Nijmegen.
'Zwarte Tulp' came to an end in 1948, and when the state of war with Germany officially ended on 26 July 1951, the remaining Germans were no longer regarded as state enemies.