He was the son of Prince August of Saxe-Coburg and his wife Clémentine of Orléans, daughter of King Louis Philippe I of the French.
Ferdinand was raised in his parents’ Catholic faith and baptised in St. Stephen's Cathedral, Vienna on 27 February, having as godparents Archduke Maximilian of Austria and his wife Princess Charlotte of Belgium.
The House of Koháry descended from an immensely wealthy Upper Hungarian noble family, who held the princely lands of Čabraď and Sitno in present-day Slovakia, among others.
[5] Ferdinand, who was an officer in the Austro-Hungarian army, was elected Prince of autonomous Bulgaria by its Grand National Assembly on 7 July 1887 in the Gregorian calendar (the "New Style" used hereinafter).
Ferdinand's accession was greeted with disbelief in many of the royal houses of Europe; Queen Victoria, his father's first cousin, stated to her prime minister, "He is totally unfit ... delicate, eccentric and effeminate ... Should be stopped at once.
[9] The Bulgarian Declaration of Independence was proclaimed by him at the Holy Forty Martyrs Church in Tarnovo, and was recognized by the Ottoman Empire and the other European powers.
A tussle broke out over where his private railway carriage would be positioned in relation to the heir presumptive to the Austro-Hungarian throne, Archduke Franz Ferdinand.
In the original documents for the Balkan League, Serbia had been pressured by Bulgaria to hand over most of Vardar Macedonia after it had conquered it from the Ottoman Empire.
However Serbia, in response to the new Albanian state receiving territory in the north that it had expected to gain for itself, said that it would keep possession of the areas that its forces had occupied.
Soon after, Bulgaria began the Second Balkan War when it invaded its recent allies Serbia and Greece to seize disputed areas, before being attacked itself by Romania and the Ottoman Empire.
This ranging of his country with the Central Powers made him a de facto supporter of Germany's war aims and was not well received by the Allies.
Edmund Gosse wrote: “In this war, where the ranks of the enemy present to us so many formidable, sinister, and shocking figures, there is one, and perhaps but one, which is purely ridiculous.
If we had the heart to relieve our strained feelings by laughter, it would be at the gross Coburg traitor, with his bodyguard of assassins and his hidden coat-of-mail, his shaking hands and his painted face.
To satisfy dynastic obligations and to provide his children with a mother figure, Ferdinand married Princess Eleonore Reuss of Köstritz, on 28 February 1908.
[18] Neither romantic love or physical attraction played any role, and Ferdinand treated her as no more than a member of the household, and showed scant regard.
[20] He was remembered in his cousin's memoir: "Prince Ferdinand, who was a Coburg, was a cousin of my father’s, and I remember the latter saying, when we got back to the hotel, that being the youngest of his family he was naturally looked upon as a fool, “ But,” said my father, “ for the fool of the family he has not done so badly for himself and I should not be surprised if he did not prove them all to be wrong.” He was always mocked at by his relations for covering himself with orders and decorations created by himself, and he was rudely nicknamed “ the Christmas-tree,”"[21] After his abdication, Ferdinand returned to live in Coburg, Germany.
[22] He commented, "Kings in exile are more philosophic under reverses than ordinary individuals; but our philosophy is primarily the result of tradition and breeding, and do not forget that pride is an important item in the making of a monarch.
Ferdinand was not displeased with exile and spent much of his time devoted to artistic endeavors, gardening, travel and natural history.
"[25] In 1947, Ferdinand (then 86 years old) secretly married his 26-year-old assistant Alžbeta Brezáková in Bamberg, Germany,[26] much to the displeasure of the members of his family.
The coffin was taken down and carried by national guards and solemnly placed in a hearse which left for the royal Vrana Palace on the outskirts of Sofia, where Ferdinand I was buried.