Boris III was the King of Bulgaria, who eventually joined the Axis side after pressure from HITLER. Bulgaria’s position initially was difficult because Boris had married an Italian princess which had made him oppose a Balkan anti-Italian pact. He was anxious to conserve Bulgarian neutrality but was too weak to stand alone. In November 1940 Boris met Hitler at Berchtesgaden and was able to leave without committing himself but eventually agreed to sign a pact with Germany. In March 1941 Boris declared war on Great Britain and six months later on the USA but refused to declare war on the USSR. On 28 August 1943 he died under mysterious circumstances shortly after an interview with Hitler. It is probable that he died of natural causes, possibly a heart attack, since no secret service claimed responsibility for his death.