King Ferdinand I of Romania reigned from 1914 to 1927. He ruled during World War I and led Romania to join the Allied forces against Germany and Austria-Hungary. After the war, Romania unified various territories and Ferdinand crowned himself as the first king of Greater Romania in 1922. Ferdinand passed away in 1927 after battling colon cancer and was buried at Curtea de Arges Monastery, leaving his young son Mihai to succeed him under a regency.