Constantine II became the last King of Greece following the death of his father, King Paul I, on March 6, 1964. The young Constantine, only 23 years old at the time, was proclaimed king in a ceremony held in Athens. His ascension came during a politically turbulent period in Greece, marked by social unrest and a shifting political landscape. The ceremony was steeped in tradition, drawing on centuries of monarchy in Greece, signifying a moment of continuity amidst impending change.

King Constantine II's reign was characterized by significant challenges. He faced opposition from the political left, rising tensions with the colonels' regime, and a deeply divided nation. The political climate continued to deteriorate, and Constantine’s attempts to navigate the complex landscape often put him at odds with political leaders. His reign was marked by both hope for modernization and mounting discontent among various factions within Greek society.

As political instability continued, Constantine II was compelled to take decisive action in 1967 but his attempts were met with failure. A coup in April of that year resulted in him being forced into exile, effectively ending the monarchy. The monarchy was officially abolished in 1973, marking a significant shift in Greece's governance. Ultimately, Constantine II's short reign became a pivotal moment in the transition of Greece from a monarchy to a republic, reshaping the country's political identity for years to come.