Frederick Charles, Prince of Schwarzburg-Rudolstadt
Prince Frederick Charles of Schwarzburg- Rudolstadt( 7 June 1736 – 13 April 1793) was a German Natural History collector, and from 1790 until his death the reigning Prince of Schwarzburg- Rudolstadt.
John Frederick, Prince of Schwarzburg-Rudolstadt
John Frederick, Prince of Schwarzburg-Rudolstadt (8 January 1721 in Rudolstadt – 10 July 1767 in ibid) was the ruling Prince of Schwarzburg-Rudolstadt from 1744 to 1767.
Friedrich Günther, Prince of Schwarzburg-Rudolstadt
Friedrich Günther, Prince of Schwarzburg-Rudolstadt (6 November 1793 – 28 June 1867) was a sovereign prince of Schwarzburg-Rudolstadt.
Louis Frederick II, Prince of Schwarzburg-Rudolstadt
Louis Frederick II, Prince of Schwarzburg-Rudolstadt (Rudolstadt, 9 August 1767 – Rudolstadt, 28 April 1807) was from 1793 to 1807 reigning Prince of Schwarzburg-Rudolstadt.
Frederick Francis II, Grand Duke of Mecklenburg-Schwerin
Frederick Francis II (28 February 1823 – 15 April 1883) was a Prussian officer and Grand Duke of Mecklenburg-Schwerin from 7 March 1842 until 15 April 1883.
Albert, Prince of Schwarzburg-Rudolstadt
Albert, Prince of Schwarzburg- Rudolstadt( 30 April 1798 – 26 November 1869) was a sovereign prince of Schwarzburg- Rudolstadt.
Albrecht VII, Count of Schwarzburg-Rudolstadt
Albrecht VII, Count of Schwarzburg-Rudolstadt (16 January 1537 – 10 April 1605) was Count of Schwarzburg and founder of the Line of Schwarzburg-Rudolstadt, which later received the title of Prince.
He was the youngest of the surviving sons of Günther XL, Count of Schwarzburg-Blankenburg and his wife Countess Elisabeth zu Ysenburg-Büdingen in Birstein.
Princess Marie of Schwarzburg-Rudolstadt
Princess Marie of Schwarzburg-Rudolstadt (29 January 1850 – 22 April 1922) was the consort and third wife of Frederick Francis II, Grand Duke of Mecklenburg-Schwerin.
She was mother of Prince Hendrik, consort of Queen Wilhelmina of the Netherlands and father of Queen Juliana.
George Albert, Prince of Schwarzburg-Rudolstadt
Georg Albert, Prince of Schwarzburg-Rudolstadt (23 November 1838 - 19 January 1890) was the penultimate sovereign prince of Schwarzburg-Rudolstadt.
Princess Anna Sophie of Schwarzburg-Rudolstadt
Princess Anna Sophie of Schwarzburg- Rudolstadt
( 9 September 1700 – 11 December 1780) was a Princess of Schwarzburg- Rudolstadt.
She was the daughter of Louis Frederick I, Prince of Schwarzburg- Rudolstadt( 15 October 1667 – 24 June 1718) and Anna Sophie of Saxe- Gotha- Altenburg( 1670 – 1728).

Question: When did Princess Marie Of Schwarzburg-Rudolstadt's husband die?
Answer: 15 April 1883