The Kingdom of Montenegro was proclaimed on 28 August 1910 by Prince Nicholas of Montenegro, who had ruled the Principality of Montenegro since 1860. Thus he became King Nicholas I of Montenegro. He had been married to Milena Vukotić since 1860 and she became the first and last Queen consort of Montenegro.
Montenegro joined the First Balkan War in 1912 during which it hoped to expand its territories. The Second Balkan War broke out in 1913 during which Serbia, joined by King Nicholas, fought against Bulgaria. During the First World War, Montenegro sided with the Triple Entente and was occupied by Austria-Hungary from 1916 until 1918.
On 26 November 1918, Nicholas I was deposed and Montenegro was unified with Serbia. The royal family was forced into exile. Nicholas died in 1921 in France, followed by Milena two years later. Their remains, together with those of two of her daughters, were transferred to Montenegro in 1989 and buried in the Cipur chapel.
The current claim to the throne of Montenegro is being held by their grandson, also named Nicholas. Montenegro officially became the Republic of Montenegro on 22 October 2007.