Besides the absence of the guest of honor, the celebrations were strange for another reason: With nearly seven decades in power, Bhumibol is the world's longest-serving head of state—and he's somehow achieved this milestone in a country that has seen more coups than most any other. By one count, there have been 10 since Bhumibol assumed the throne after his brother, the previous king, was found shot in the head in 1946. As elected leaders and military juntas have come and gone in Thailand with a frequency unrivaled in the world, King Bhumibol has held on at the very top, and he is frequently described as a "unifying force" in a country with deep political divisions. How has he done it?