In 1858, Prince Alexander went into exile along with his son.
Most of this exile was spent in France.
Peter I received his education there and also took active part in the Franco-Prussian War in 1871.
In 1883, he married Princess Zorka of Montenegro, daughter of King Nicholas I.
On 11 June 1903, Peter was made the King of Serbia after King Alexander was removed through a military coup d'état.
However, due to ill health Peter chose to retire once the Balkan Wars were over and passed on executive powers to his son Alexander.
Even though he ruled over Serbia only from 1903-1921, he tried to use his western education to try and liberalize Serbia and to create a constitutional monarchy in line with the western styles.
He also used to visit trenches to check on his troops occasionally during World War I, in spite of being relatively inactive during that period.
During one such visit, it is said that Peter actually picked up a rifle and shot at enemy soldiers and this was at the age of 71.
On December 1, 1918, he was announced as the King of Serbs, Croats and Slovenes and this was his last public appearance.
He died in 1921 at the ripe old age of 77 in Belgrade.
King Peter I was well known for his modesty and was immensely popular throughout his reign and is considered as one of the most popular leaders of Western Balkans.
He is also considered to be the founder of Yugoslavia.