Philip, Duke of Holstein-Gottorp
Philip, Duke of Holstein- Gottorp( 10 August 1570 – 18 October 1590) was the second son of Adolf, Duke of Holstein- Gottorp( 1526 – 1586) and his wife, Christine of Hesse( 1543 – 1604).
After the early death of his elder brother Frederick II in 1587, he inherited the ducal share of rule in the royal Danish- ducal condominium of the duchies of Holstein and of Schleswig at the age of 17.
He died three years later.
Christian August, Prince of Anhalt-Zerbst
Christian August, Prince of Anhalt-Zerbst (29 November 1690, in Dornburg – 16 March 1747, in Zerbst) was a German prince of the House of Ascania.
He was a ruler of the Principality of Anhalt-Dornburg, then, from 1742, a ruler of the entire Principality of Anhalt-Zerbst.
He was also a Prussian "Generalfeldmarschall", but is best known for being the father of Catherine the Great of Russia.
Adolf, Duke of Holstein-Gottorp
Adolf of Denmark or Adolf of Holstein-Gottorp (25 January 1526 – 1 October 1586) was the first Duke of Holstein-Gottorp from the line of Holstein-Gottorp of the House of Oldenburg.
He was the third son of King Frederick I of Denmark and his second wife, Sophie of Pomerania.
King Frederick I had his son educated by Philip I, Landgrave of Hesse.
He spent four years at the Landgrave's castle in Kassel.
In 1544, Adolf, his brother Johann, and their half-brother King Christian III of Denmark, divided the duchies of Schleswig and Holstein.
The areas were divided according to approximately equal tax proceeds.
Adolf, as the youngest, was entitled the first choice.
Since he selected the part with the castle Gottorp, the line of the house Oldenburg created by him was called "Schleswig-Holstein-Gottorp".
Christian August of Holstein-Gottorp, Prince of Eutin
Christian August of Holstein-Gottorp-Eutin (11 January 1673 – 24 April 1726) was a cadet of the reigning ducal House of Holstein-Gottorp who became prince of Eutin, prince-bishop of Lübeck and regent of the Duchy of Holstein-Gottorp.
He was the father of Adolf Frederick, King of Sweden, and the maternal grandfather of Catherine the Great, Empress of Russia.
John Adolf, Duke of Holstein-Gottorp
Johann Adolf of Holstein- Gottorp( 27 February 1575 – 31 March 1616) was a Duke of Holstein- Gottorp.
Duchess Marie Elisabeth of Saxony
Duchess Marie Elisabeth of Saxony (22 November 1610 – 24 October 1684) was duchess consort of Holstein-Gottorp as the spouse of Duke Friedrich III of Holstein-Gottorp.
Joanna Elisabeth of Holstein-Gottorp
Johanna Elisabeth of Holstein-Gottorp (24 October 1712 – 30 May 1760) was a German regent, Princess of Anhalt-Zerbst by marriage to Christian August, Prince of Anhalt-Zerbst, and regent of Anhalt-Zerbst from 1747 to 1752 for her minor son, Frederick Augustus.
She is best known as the mother of Catherine the Great of Russia.
She was born at Gottorp, the daughter of Christian August, Duke of Holstein-Gottorp and Albertina Frederica of Baden-Durlach.
Christine of Hesse
Christine of Hesse (29 June 1543 – 13 May 1604) was Duchess consort of Holstein-Gottorp as the spouse of Duke Adolf of Holstein-Gottorp.
She exerted some political influence as a widow after 1586.
Augusta Marie of Holstein-Gottorp
Augusta Marie of Holstein- Gottorp( 1649 – 1728) was a German noblewoman.
She was the daughter of Frederick III, Duke of Holstein- Gottorp and Duchess Marie Elisabeth of Saxony.
Through her daughter Albertine Frederica, she is the great- grandmother of Catherine II and great- great- grandmother of Paul I of Russia.
She married Frederick VII, Margrave of Baden- Durlach on 15 May 1670 in Husum.
They had the following children:
Frederick II, Duke of Holstein-Gottorp
Frederick II, Duke of Holstein- Gottorp( 21 April 1568 – 15 June 1587) was a Danish- German nobleman.
He was the eldest son of Duke Adolf of Holstein- Gottorp and his wife, Christine of Hesse( 1543- 1604).
He inherited the ducal share of rule in the royal Danish- ducal condominium of the duchies of Holstein and of Schleswig when his father died in 1586, and died only a year later.

Question: When did Joanna Elisabeth Of Holstein-Gottorp's husband die?
Answer: 16 March 1747