Amanullah Khan proclaimed Afghanistan a kingdom in 1926, seven years after taking the throne. He was a modernizer who admired Ataturk's Turkey, and his reforms -- including education for women and Western-style governance -- provoked fierce resistance from conservative tribal leaders. When rebellion erupted during his 1927 trip to Europe, Amanullah abdicated in favor of his brother Inayatullah, whose three-day reign ended when Habibullah Kalakani seized power. The restored emirate lasted barely ten months. Mohammad Nadir, Amanullah's former Minister of War, returned from exile in India, ousted the Saqqawist government, executed Kalakani, and reinstated the monarchy. Crowned Mohammad Nadir Shah in October 1929, he promptly reversed his predecessor's reforms. Afghanistan would have its kingdom, but not its revolution.

When Nadir Shah was assassinated in 1933, his son Mohammad Zahir Shah inherited the throne at nineteen. He would hold it for thirty-nine years, making him the longest-reigning Afghan monarch of the modern era. Under Zahir Shah, Afghanistan joined the League of Nations in 1934, remained neutral during World War II, and cast the only vote against Pakistan's admission to the United Nations in 1947. His reign saw the country join the Non-Aligned Movement in 1961, threading a diplomatic needle between the Soviet Union and the West. In the Darai Nur valley, where the Pashayi people predominated, his government launched literacy campaigns that met an unexpected class divide: wealthier families bribed officials to keep their sons out of school, while poorer villagers, seeing nothing un-Islamic in the program, enrolled theirs.

Afghanistan's neutrality made it a prize in the superpower competition. The United States signed the Four Point Program agreement in 1951, and the Export-Import Bank provided $18.5 million for the Helmand River valley development project. The Soviets countered by building a 100-kilometer pipeline from Termez to Mazar-i-Sharif starting in 1954. Both powers poured investment into a country whose economy still relied heavily on agriculture and mining -- deposits of lapis lazuli, copper, chromite, and iron ore lay beneath the mountains, but extraction remained limited. When Pakistan closed its border in August 1961 over the Pashtunistan dispute, the economic consequences underscored just how dependent Afghanistan was on its neighbors' goodwill.

The kingdom's military became a mirror of its geopolitical entanglements. In 1956, a $32.5 million Soviet arms deal brought T-34 tanks and MiG-17 jet fighters to the Afghan military. By 1973, between a quarter and a third of all Afghan officers had trained in the Soviet Union. Yet the first Afghan commando formations drew from multiple traditions: Captain Habibullah led the 242nd Parachute Battalion after training at Fort Benning in the United States and with the British Special Air Service. Major Rahmatullah Safi, who became commander of the 444th Battalion, had studied at both the Royal Military Academy Sandhurst and the Soviet Ryazan Higher Airborne Command School. Czechoslovakia helped build the army university and a technical academy. Afghanistan's soldiers learned from everyone, and everyone expected something in return.

In July 1973, while Zahir Shah was in Italy recovering from eye surgery, his cousin and former prime minister Mohammad Daoud Khan staged a bloodless coup. Daoud had been forced to resign as prime minister a decade earlier, and the 1964 constitution -- which concentrated power under Zahir Shah's direct line -- gave him reason to act. The king, learning of the takeover from abroad, abdicated the following month to avoid civil war. With that quiet surrender, centuries of Afghan monarchy came to an end. Daoud declared a republic and installed himself as president, beginning a five-year experiment that would itself be swept away by the Saur Revolution in 1978. The kingdom had lasted forty-seven years. The peace Zahir Shah's abdication was meant to preserve would not last five.