Even then, Transylvania, and other areas were of interest to the Romanian government of the time. When Romania became a kingdom under King Carol I, it was simply another small Eastern European country, along with Greece, Bulgaria and others. There was tension between these nations, as there was across Europe.
Something was about to happen.
In 1914, in the small Kingdom of Serbia an archduke of Austria and his wife, a countess, were assassinated and this lead to the beginning of World War I. Romania would later make the choice to fight alongside the Allies, and many believe this was because of Queen Marie's influence on her husband, King Ferdinand.
It was a queen who made the suggestion that Romania should fight with the Allies, and she also went to the Paris Peace Conference and positioned Transylvania and Besserabia in the process which would increase her Kingdom. Most of this territory had many ethnic Romanians living there.
English Princess. She became Queen of Romania, where he once ruled as Prince of Wallachia.