Amanullah Khan was the leader of Afghanistan’s third war against the British. Amanullah Khan's government was guided by the bourgeois democratic ideas of Afghanistan's youth. During the administration, a cabinet was established in order to eliminate the chaos of central administration, roads were built between India and Afghanistan, new capitals and palaces were built, troops were trained and factories were built, all completed by military experts and technicians recruited from abroad. The third Anti-British War took place on May 3, 1919. The Afghan border guards in the Khyber Pass were raided by the British army. Then, the British invaded Afghanistan in three ways. The Afghan army of 40,000 men was divided into three groups to meet the enemy in Khyber, Ghazni and Kandahar. The British army has an absolute advantage in terms of strength and weapons. They are well-trained and well-equipped, and they also have a small number of armored vehicles and combat aircraft.

Nevertheless, the Afghan people fought a just war for independence and freedom with high morale and tenacity. The support of the ethnic minority rebels on the India-Afghanistan border played a very important role and finally reversed the passive situation. On May 6, the Afghan army from the Khyber direction captured the enemy Bagh Fortress with three infantry battalions and seized the favorable terrain around the Landikotal Fortress. However, they did not take the opportunity to capture the fortress and lost the fighter opportunity. With the support of the Royal Air Force, the British army recaptured the Bagh Fortress, while the Afghan army fought and retreated.

The British army carried out concentrated bombing on Jalalabad and Kabul, causing panic among the Afghan army and citizens. As the Afghan army took the initiative to attack in the middle, the British army gave up the attack on Jalalabad and was forced to divide its troops for reinforcements. On May 19, the Afghan army advanced to the important border town of Madun, commanding a commanding position and forcing the enemy to retreat. Then they took a small road and penetrated directly into the city of Taal. The deployment of the British army was destroyed. In the face of the tenacious resistance of the Afghan army and the high spirit of the Indian liberation movement, the British invaders were in a difficult situation and were forced to give up their plan to continue fighting. On June 3, the war ended and the two sides entered into negotiations. On November 22, 1921, Britain and Afghanistan signed a peace treaty, and Britain recognized Afghanistan's independence. So far, the Afghan people's war against the British has achieved complete victory.

Amanullah Khan's reforms were strongly opposed by the church's upper echelons and tribal chiefs, and the increase in taxes caused social conflicts. From 1928 to 1929, the reactionaries headed by Bach Sagao launched an anti-government riot with the support of British imperialism and occupied the capital. In January 1929, Amanullah Khan announced his abdication and went into exile in Europe.