[1] Their mother took an interest in what the brothers wore: she ordered for Ludwig to always be dressed in blue and for Otto to always wear red.

Between 1853 and 1863, the brothers spent their summer holidays at the Royal Villa in Berchtesgaden, which had been specially built for their father.

Otto was promoted to Captain on 27 April 1866 and entered active military service in the Royal Bavarian Infantry Guards.

Otto had spells during which he slept poorly for days and acted out, followed by periods of time during which he was perfectly normal and lucid.

His attending physician was Dr. Bernhard von Gudden, who later diagnosed Otto's brother, Ludwig, as mentally ill without examining him, which raises questions about his competence and his motives.

Some contemporaries also believed that Bismarck did not want Ludwig nor Otto to remain in power and decided to replace the brothers with their malleable uncle, Luitpold.

[8] During Corpus Christi Mass in 1875 in the Frauenkirche in Munich, Otto, who had not attended the church service, rushed into the church wearing hunting clothes and fell on his knees before the celebrant, Archbishop Gregor von Scherr, to ask forgiveness for his sins.

Otto's last public appearance was his presence at the side of his brother at the King's parade on 22 August 1875, at the Marsfeld in Munich.

[11] In 1894, Otto had shown signs of recovery and was cleared to attend a fête champêtre at Bamberg where he smashed sixty-five bottles of 'high grade champagne'.

Only three days later Ludwig II died under unknown circumstances, and Prince Otto succeeded him as King of Bavaria on 13 June 1886 in accordance with the Wittelsbach succession law.

Since Otto was unable to lead the government due to his mental illness (officially it was said: "The King is melancholic"), Prince Regent Luitpold also reigned for him.

Shortly thereafter, the Bavarian Army troops were sworn in the name of King Otto I and coins were minted with his portrait.

[13] Luitpold kept his role as Prince Regent until he died in 1912 and was succeeded by his son Ludwig, who was Otto's first cousin.

Accordingly, the constitution of Bavaria was amended on 4 November 1913 to include a clause specifying that if a regency for reasons of incapacity lasted for ten years, with no expectation that the King would ever be able to reign, the Regent could end the regency, depose the King and assume the crown himself with the assent of the legislature.