Wilhelm Friedrich, Duke of Schleswig-Holstein
Friedrich, Duke of Schleswig- Holstein- Sonderburg- Glücksburg, from 1934 Duke of Schleswig- Holstein( 23 August 1891 – 10 February 1965), was the Duke of Schleswig- Holstein and Head of the House of Oldenburg from 21 January 1934 until his death on 10 February 1965.
Friedrich Ferdinand, Duke of Schleswig-Holstein
Friedrich Ferdinand of Schleswig- Holstein- Sonderburg- Glücksburg( 12 October 1855 – 21 January 1934) was the fourth Duke of Schleswig- Holstein- Sonderburg- Glücksburg and became Duke of Schleswig- Holstein in 1931.
Albert, Duke of Schleswig-Holstein
Albert, Duke of Schleswig- Holstein( Albert John Charles Frederick Alfred George; 26 February 1869 – 27 April 1931), was a grandson of Queen Victoria.
He was the second son of Victoria's daughter, Princess Helena, by her husband Prince Christian of Schleswig- Holstein.
He was the head of the House of Oldenburg and also the House of Schleswig- Holstein- Sonderburg- Augustenburg and the Duke of Schleswig- Holstein between 1921 and 1931.
Christian IV of Denmark
Christian IV (12 April 1577 – 28 February 1648) was king of Denmark and Norway and duke of Holstein and Schleswig from 1588 to 1648.
His 59-year reign is the longest of Danish monarchs, and of Scandinavian monarchies.
A member of the house of Oldenburg, Christian began his personal rule of Denmark in 1596 at the age of 19.
He is remembered as one of the most popular, ambitious, and proactive Danish kings, having initiated many reforms and projects.
Christian IV obtained for his kingdom a level of stability and wealth that was virtually unmatched elsewhere in Europe.
He engaged Denmark in numerous wars, most notably the Thirty Years' War (1618–48), which devastated much of Germany, undermined the Danish economy, and cost Denmark some of its conquered territories.
He rebuilt and renamed the Norwegian capital Oslo as "Christiania" after himself, a name used until 1925.
Joachim Frederick, Duke of Schleswig-Holstein-Sonderburg-Plön
Joachim Frederick of Schleswig-Holstein- Sonderburg- Plön( 9 May 1668, Magdeburg – 25 January 1722, Plön), also known as Joachim Frederick of Schleswig- Holstein- Plön, was the third Duke of Schleswig- Holstein- Plön, a dukedom created by the division of the Duchy of Schleswig- Holstein- Sonderburg.
Princess Alexandra Victoria of Schleswig-Holstein-Sonderburg-Glücksburg
Princess Alexandra Victoria of Schleswig-Holstein- Sonderburg- Glücksburg( 21 April 1887 – 15 April 1957) was a daughter of Friedrich Ferdinand, Duke of Schleswig- Holstein and his wife Princess Karoline Mathilde of Schleswig- Holstein- Sonderburg- Augustenburg.
Princess Marie Alexandra of Schleswig-Holstein
Princess Marie Alexandra of Schleswig-Holstein -Sonderburg- Glücksburg, since 1941 of Schleswig- Holstein( Marie Alexandra Caroline- Mathilde Viktoria Irene; 9 July 1927, Schloss Louisenlund, Schleswig, Schleswig- Holstein, Germany – 14 December 2000, Friedrichshafen, Baden- Württemberg, Germany) was a member of the House of Schleswig- Holstein- Sonderburg- Glücksburg.
Marie Alexandra was the fourth and youngest child of Wilhelm Friedrich, Duke of Schleswig- Holstein and his wife Princess Marie Melita of Hohenlohe- Langenburg.
Her older brother Peter was the Duke of Schleswig- Holstein and Head of the House of Oldenburg from 10 February 1965 until his death on 30 September 1980.
Joachim Ernest, Duke of Schleswig-Holstein-Sonderburg-Plön
Joachim Ernest of Schleswig-Holstein- Sonderburg- Plön( 29 August 1595 – October 5, 1671), also" Joachim Ernest of Schleswig- Holstein- Plön", was the first Duke of Schleswig- Holstein- Sonderburg- Plön, which emerged from a division of the Duchy of Schleswig- Holstein- Sonderburg.
Valdemar Christian of Schleswig-Holstein
Valdemar Christian of Schleswig-Holstein (1622–February 26, 1656) was the son of king Christian IV of Denmark and his morganatic spouse Kirsten Munk.
He had the title Count of Schleswig-Holstein.
Friedrich, Duke of Schleswig-Holstein-Sonderburg-Glücksburg
Friedrich of Schleswig- Holstein- Sonderburg- Glücksburg( 23 October 1814 in Schleswig, Duchy of Schleswig – 27 November 1885 in Luisenlund, Schleswig- Holstein, Prussia) was the third Duke of Schleswig- Holstein- Sonderburg- Glücksburg.
Friedrich was the second- eldest son of Friedrich Wilhelm, Duke of Schleswig- Holstein- Sonderburg- Glücksburg and Princess Louise Caroline of Hesse- Kassel and an elder brother of Christian IX of Denmark.
Friedrich inherited the title of Duke of Schleswig- Holstein- Sonderburg- Glücksburg upon his childless brother Karl's death on 14 October 1878.

Question: What is the date of death of Valdemar Christian Of Schleswig-Holstein's father?
Answer: 28 February 1648