Afghanistan became the focus of international conflict in the nineteenth century. The British sought to protect India from the Russians. In an effort to stop the Russians, Britain brought pressure on Afghanistan, which resulted in two British-Afghan wars, one from 1839 to 1842 and the other from 1878 to 1880.
British forces first pushed into Afghanistan in 1839, taking Kandahar and Kabul. Tribal opposition led to the withdrawal of the troops in 1842. During this withdrawal, almost all the British troops were killed by Afghan tribal warriors. The Second Afghan War erupted in 1878 over British concerns about negotiations between Shir Ali Khan, who ruled Afghanistan from 1863 to 1878, and the Russians.
Once again, Great Britain was afraid of Russian interference with the Indian border. The conflict ended when Abdur Rahman Khan became Afghanistan's ruler in 1880. He ruled until 1901, promoting the idea of national unity and diminishing the power of the warlike tribes. In 1893 he talked with the British and established the Durand Line, the boundary between Afghanistan and Pakistan that remained into the late twentieth century.
Habibullah Khan reigned next. He succeeded in keeping Afghanistan neutral during World War I. The British retained control over Afghanistan's foreign relations until 1919.
The Third Afghan War with Britain occurred in 1919. At this time Britain gave up any interest in Afghanistan's external or internal relations. Amanullah Khan, who reigned from 1919 to 1929, promoted many reforms in Afghanistan. He wanted a more efficient administration, a constitution, and a modern social structure. His plans outraged many of the traditional religious and tribal leaders. Kabul was seized by Afghan rebels in 1929, and Amanullah abdicated and left the country.
Nadir Shah Ghazi became the new ruler, but internal strife resulted in his assassination in 1933. Mohammed Zahir Shah, Nadir Shah Ghazi's oldest son, was declared king upon Nadir's death. Mohammed's uncles and cousins were influential throughout the country during this time. The traditional policy of isolation was abandoned, and the first factories, roads, and irrigation projects were begun. Afghanistan remained neutral in World War II, but the resulting lack of trade in the country strained the economy.