Peter II (Petar II), of the Karadjordjevic dynasty, succeeded in 1934 after the assassination while on a state visit to France of his father, King Alexander I, under a regency headed by his father's cousin, Prince Pavle. 18 years old King Peter participated in a British-supported coup d'état on March 27th, 1941, opposing the Regent's signing the Tripartite Pact.
Although King Peter and his advisors opposed Nazi-Germany, they also feared that if Hitler attacked Yugoslavia, Britain was not in any real position to help. For the safety of the country, they declared that Yugoslavia would adhere to the Tripartite Pact.
Postponing Operation Barbarossa Germany simultaneously attacked Yugoslavia and Greece. From April 6th, Luftwaffe pounded Belgrade to the ground for three days and three nights. German ground troops moved in, and Yugoslavia capitulated on April 17th. King Petar fled the country following the German invasion.
He married Princess Alexandra of Greece and Denmark, in London 1944.
King Peter was deposed after World War II by Yugoslavia's Constituent Assembly on November 29th, 1945, while still in exile. He died in Denver, Colorado on 3 November 1970. He is interred at Libertyville, Illinois, the only European monarch buried on American soil.
His son, Crown Prince Alexander is pretender to the Serbian throne.