Question: What famous public holiday celebrates the events that led to the closing of the Grini prison camp? 

Context articles: Victory in Europe Day
Veidal Prison Camp
Zhongma Fortress
Stage Flag Day (Kyrgyzstan)
Gaecheonjeol
Navy Day (Ukraine)
Grini detention camp
May 3rd Constitution Day
Camp Cusino
Garifuna Settlement Day

Victory in Europe Day, generally known as V-E Day, VE Day or simply V Day, was the public holiday celebrated on 8 May 1945 to mark the formal acceptance by the Allies of World War II of Nazi Germany's unconditional surrender of its armed forces.
 It thus marked the end of World War II in Europe.
The Veidal Prison Camp (Norwegian: "Veidal fangeleir" , German: "Gefangenenlager Veidal Kvænangen" ) was established in Kvænangen in August 1942 by the German occupation authorities.
 The prison camp was a subunit of the Grini Prison Camp and, together with the Badderen Prison Camp, was created to erect snow fences and build snow sheds along a 6 km length of roadway over the mountain Kvænangsfjellet.
 Four hundred prisoners from the Grini camp were sent to Kvænangsfjellet to assist Norwegian civilian laborers with the construction.
 The prisoners remained on the mountain for three months, from August 14, 1942 to November 11, 1942.
Zhongma Fortress — or Zhong Ma Prison Camp, or Unit Tōgō — was a prison camp where the Japanese Kwantung Army carried out covert biological warfare research on human test subjects.
 Built in Beiyinhe, outside of Harbin, Manchukuo during the Second Sino-Japanese War, the camp served as a center for human subject experimentation and could hold up to 1,000 prisoners at any given time.
 In 1937 the prison camp was destroyed and testing operations were transferred to Pingfang under Unit 731.
State Flag Day is public holiday of Kyrgyzstan.
 This holiday has been celebrated March 3 since 2010.
 The holiday celebrates the adoption of the Flag of Kyrgyzstan on March 3, 1992.
Gaecheonjeol (Korean: 개천절 , hanja: 開天節) is a public holiday in South Korea on 3 October.
 Also known by the English name National Foundation Day, this holiday celebrates the legendary formation of the first Korean state of Gojoseon in 2333 BC.
 This date has traditionally been regarded as the date for the founding of the Korean nation.
Day of the Holiday of the Ukrainian Navy (Ukrainian:День працівників морського та річкового флоту України) is national holiday in Ukraine.
 The holiday celebrates the founding of the Ukrainian Navy.
Grini prison camp (Norwegian: "Grini fangeleir" , German: "Polizeihäftlingslager Grini" ) was a Nazi concentration camp in Bærum, Norway, which operated between 1941 and May 1945.
 Ila Detention and Security Prison is now located here.
3rd May National Holiday (also "May 3rd Constitution Day"; Polish: "Święto Konstytucji 3 Maja" ) is a Polish national and public holiday that takes place on 3rd May.
 The holiday celebrates the declaration of the Constitution of May 3, 1791.
 Festivities date back to the Duchy of Warsaw early in the 19th century, but it became an official holiday only in 1919 in the Second Polish Republic.
 Delisted during the times of the People's Republic of Poland, it was reestablished after the fall of communism in modern Poland.
Camp Cusino was created in 1951.
 It is located one mile west of Shingleton, Michigan.
 The camp was officially called the Cusino Corrections Prison Work Camp and was part of the Corrections Conservation Prison Camp Program in the State of Michigan.
 The name Cusino was taken from a Civilian Conservation Corps (CCC) camp that was located four miles east of Melstrand, Michigan.
 In 1951, some of the CCC buildings were moved to Shingleton for the prison camp.
 The inmates were trustee status and many worked for the neighboring Cusino Wildlife Research Station.
 Other inmates were transported daily to do timber stand improvement and maintain area state parks.
 In 1968 the camp held 93 prisoners with nine staff.
 In 1979 the old wooden barracks were replaced with modern block buildings.
 In 1996 the prison camp population was 350.
 The security level of the prisoners was increased and the camp proper was fenced in with cyclone/razor wire fencing.
Garifuna Settlement Day is a public holiday in Belize, celebrated each year on November 19.
 The holiday was created by Belizean civil rights activist, Thomas Vincent Ramos, in 1941.
 It was recognized as a public holiday in the southern districts of Belize in 1943, and declared a national holiday in 1977.
 The holiday celebrates the settlement of the Garifuna people in Belize after being exiled from the Grenadines by the British army.
 The major festivities for the holiday occur in the town of Dangriga, including parades, street music, and traditional dancing.