Question: When was the king who was the subject of Siegfried Obermeier's "The Secret Diaries of Ludwig II of Bavaria" born? 

Context paragraphs:
Ludwig II (2012 film): Ludwig II is a 2012 film directed by and Marie Noëlle, starring as the younger Bavarian King Ludwig II and Sebastian Schipper as the king in his later years.

Ludwig II of Bavaria: Ludwig II (German: "Ludwig Otto Friedrich Wilhelm" ; English: Louis Otto Frederick William ; 25 August 1845 – 13 June 1886) was King of Bavaria from 1864 until his death in 1886.  He is sometimes called the Swan King, Mad King Ludwig or der Märchenkönig (the 'Fairy Tale King').  He also held the titles of Count Palatine of the Rhine, Duke of Bavaria, Duke of Franconia, and Duke in Swabia.

Ludwig II (manga): Ludwig II (Japanese: ルートヴィヒⅡ世 , Hepburn: Rūtovihi II Sei ) is a Japanese manga series written and illustrated by You Higuri.  It is licensed in North America by Digital Manga Publishing, which released the first volume of the manga on 10 June 2009, and the second on 23 September 2009.  It has been licensed in France and Germany by Panini Comics.  It fictionalises the story of Ludwig II of Bavaria.

Siegfried Obermeier: Siegfried Obermeier (Munich, 21 January 1936 - Oberschleißheim near Munich, 21 January 2011) was a German author of historical novels and popular history books.  He was editor of The Secret Diaries of Ludwig II of Bavaria 1976.  In 1978 he issued his first novel, initially under the penname Carl de Scott, a novelisation of the second life of Judas Iscariot.  His Jesus in India book "Starb Jesus in Kaschmir?"  made it to the Year Bestseller List of the Spiegel in 1983.

Ludwig: Requiem for a Virgin King: Ludwig: Requiem for a Virgin King (German: Ludwig – Requiem für einen jungfräulichen König ) is a 1972 West German historical drama film directed by Hans-Jürgen Syberberg, starring Harry Baer as Ludwig II of Bavaria.  The film was shot on a soundstage with rear-projected scenography and an intentionally artificial style.

Ludwig II, King of Bavaria: Ludwig II, King of Bavaria (German: Ludwig der Zweite, König von Bayern) is a 1929 German silent historical film directed by William Dieterle and starring Dieterle, Theodor Loos and Eugen Burg.  It portrays the life and reign of the monarch Ludwig II who ruled Bavaria from 1864 to 1886.  It was made at the Bavaria Studios in Geiselgasteig, Munich.  The production company was the German subsidiary of the American studio Universal Pictures.

Hohenschwangau Castle: Hohenschwangau Castle or Schloss Hohenschwangau (lit: "Upper Swan County Palace") is a 19th-century palace in southern Germany.  It was the childhood residence of King Ludwig II of Bavaria and was built by his father, King Maximilian II of Bavaria.  It is located in the German village of Hohenschwangau near the town of Füssen, part of the county of Ostallgäu in southwestern Bavaria, Germany, very close to the border with Austria.

Berg Castle (Bavaria): Berg Castle (German: "Schloss Berg" ) is a manor house situated on the east shore of Lake Starnberg in the village of Berg in Upper Bavaria, Germany.  It is famous as the site of King Ludwig II of Bavaria's death.  Today, it remains home to the head of the house of Wittelsbach, currently Franz, Duke of Bavaria.

Luitpold, Prince Regent of Bavaria: Luitpold, Prince Regent of Bavaria (German: "Prinzregent Luitpold Karl Joseph Wilhelm Ludwig von Bayern" ) (12 March 1821 – 12 December 1912), was the "de facto" ruler of Bavaria from 1886 to 1912, due to the incapacity of his nephews, King Ludwig II for three days and King Otto for 26 years.

Louis II, Duke of Bavaria: Ludwig I or Louis I of Upper Bavaria (German: "Ludwig II der Strenge, Herzog von Bayern, Pfalzgraf bei Rhein" ) (13 April 1229 – 2 February 1294) was Duke of Upper Bavaria and Count Palatine of the Rhine from 1253.  He is known as Ludwig II or Louis II as Duke of Bavaria, and also as Louis the Strict.  Born in Heidelberg, he was a son of duke Otto II and Agnes of the Palatinate.  She was a daughter of the Welf Henry V, Count Palatine of the Rhine, her grandfathers were Henry XII the Lion and Conrad of Hohenstaufen.

Supporting paragraphs: Siegfried Obermeier Ludwig II of Bavaria
Answer: 25 August 1845