More information is necessary.
If you are referring to the poem "In Flanders Fields" (written in 1915) then it is in the public domain. If you mean the book "In Flanders Fields: The 1917 Campaign," by Leon Wolff then the copyright would, in all likelihood, belong to either the author or whomever he assigned the copyright to because the book was written in 1958. Just the phrase "Flanders Fields" would not qualify for copyright protection but may be registered as a trademark.
Samuel Beckett's estate owns the copyrights and the estate is currently run by his nephew.
Flanders is in Belgium.
In Flanders Fields - John McCrae
Flanders Fields is the name given to the battlefields from World War I. The fields are located between West Flanders and East Flanders in Belgium.
The foe referred to in the poem "In Flanders Fields" by John McCrae is the enemy soldiers fighting on the opposing side during World War I. They are portrayed as the adversaries to the soldiers and victims memorialized in Flanders Fields.
Brentwood-Benson.
The poem "In Flanders Fields" by John McCrae was written during the Second Battle of Ypres.Ypres is a city in Belgium.
Colonel McCrae was in Canada when he wrote In Flanders Fields. He was in hospital after being shot.
Random House.
US TREASURY!!!
1915
In Flanders Fields which is where the war was