Question: The Fate of the House of Habsburg, is a 1928 German silent drama film, it s based on the Mayerling incident, the series of events leading to the apparent murder–suicide of Rudolf, Crown Prince of Austria, and his lover, Baroness Mary Vetsera, in which year?

Context paragraphs:
Rudolf (musical): Rudolf is a musical conceived for the stage by Frank Wildhorn and Steve Cuden, with a book by Jack Murphy and Phoebe Hwang, lyrics by Murphy, additional lyrics by Nan Knighton, and music by Frank Wildhorn.  Arrangements by Koen Schoots and orchestrations by Kim Scharnberg.  It is about Rudolf, Crown Prince of Austria and his extramarital relationship with Baroness Mary Vetsera.  Their 1889 deaths at his Mayerling hunting lodge apparently were the result of a murder-suicide pact, although historians have debated this explanation.

Alma Vetsera Hayne: Alma Vetsera Hayne (1890–1919) was a New York City socialite who passed herself off as the daughter of Rudolf, Crown Prince of Austria and Baroness Mary Vetsera and called herself Princess Vetsera of Austria.  She claimed her son, Rudolph Hayne (1899-?) , was heir to the Austro-Hungarian throne.

Rudolf, Crown Prince of Austria: Rudolf, Crown Prince of Austria (Rudolf Franz Karl Joseph; 21 August 1858 – 30 January 1889) was the only son of Emperor Franz Joseph I and heir apparent to the throne of Austria-Hungary from birth.  In 1889, he died in a suicide pact with his mistress, Baroness Mary Vetsera, at the Mayerling hunting lodge.  The ensuing scandal made international headlines.  He was named after the first Habsburg King of Germany, Rudolf I, who assumed the throne in 1273.

Tragedy in the House of Habsburg: Tragedy in the House of Habsburg (German: Tragödie im Hause Habsburg) is a 1924 German silent historical film directed by Alexander Korda and starring María Corda, Kálmán Zátony and Emil Fenyvessy.  The film recounts the events of the 1889 Mayerling Incident in which the heir to the Austro-Hungarian Empire committed suicide.  Studio filming was done in Berlin with location shooting in Vienna.  The film cost $80,000 to make, but only earned back around half of this at the box office.

Crown Prince Rudolph's Last Love: Crown Prince Rudolph's Last Love (German: Kronprinz Rudolfs letzte Liebe/Mayerling) is a 1955 Austrian historical drama film directed by Rudolf Jugert and starring Rudolf Prack, Christiane Hörbiger and Winnie Markus.  The film portrays the tragic 1889 Mayerling Incident, in which Rudolf, Crown Prince of Austria and his lover Baroness Mary Vetsera committed suicide.

The Fate of the House of Habsburg: The Fate of the House of Habsburg (German: Das Schicksal derer von Habsburg) is a 1928 German silent drama film directed by Rolf Raffé and starring Fritz Spira, Alphons Fryland and Leni Riefenstahl.  It is based on the Mayerling incident of 1889.

Baroness Mary Vetsera: Baroness Marie Alexandrine von Vetsera (19 March 1871 – 30 January 1889) was a member of Austrian "second society" (new nobility) and one of Crown Prince Rudolf of Austria's mistresses.  Vetsera and Rudolf were found dead, an apparent murder suicide, at his hunting lodge, Mayerling (see Mayerling Incident).

Mayerling incident: The Mayerling Incident is the series of events leading to the apparent murder–suicide of Rudolf, Crown Prince of Austria (21 August 1858 – 30 January 1889) and his lover, Baroness Mary Vetsera (19 March 1871 – 30 January 1889).  Rudolf was the only son of Emperor Franz Joseph I of Austria and Empress Elisabeth, and heir to the throne of the Austro-Hungarian Empire.  Rudolf's mistress was the daughter of Baron Albin Vetsera, a diplomat at the Austrian court.  The bodies of the 30-year-old Archduke and the 17-year-old baroness were discovered in the Imperial hunting lodge at Mayerling in the Vienna Woods, fifteen miles southwest of the capital, on the morning of 30 January 1889.

Marinka (operetta): Marinka is an operetta by Hungarian composer Emmerich Kálmán with book by George Marion, Jr. and Karl Farkas, and lyrics by George Marion, Jr.  The operetta is a retelling of the story of the Mayerling Incident, but with a happy ending replacing the infamous 1889 double suicide of Austrian Crown Prince Rudolf and his mistress, Maria Vetsera.  The best-known songs include "Only One Touch of Vienna," "Sigh by Night," "The Cab Song," and "When I Auditioned for the Harem of the Shah".

Princess Stéphanie of Belgium: Princess Stéphanie of Belgium (21 May 1864 – 23 August 1945) was a Belgian princess by birth and became Crown Princess of Austria through her marriage to the heir-apparent of the Habsburg dynasty, Archduke Rudolf.  She was famously widowed in 1889 when Rudolf and his mistress, Mary Vetsera, were found dead in an apparent murder-suicide pact at the Imperial hunting lodge at Mayerling in the Vienna Woods.

Supporting paragraphs: The Fate of the House of Habsburg Mayerling incident
Answer: 1889