Oman Nura Khan's action for national independence has been actively supported by people from all walks of life in Afghanistan, but it has been strongly opposed by British imperialism. Britain is determined to use force again to force Afghans to submit. On May 3, 1919, 34, British troops gathered in khyber pass on the India-Afghanistan border and launched the third colonial war of aggression against Afghanistan in history. Oman Nura Khan did not give in to the British. At the mass meeting of Idgah Mosque in Kabul, he called on the people to devote themselves to jihad at all costs. After the outbreak of the war, the main force of the British army attacked Jalalabad on the northern line via khyber pass, one attacked Kandahar with weak defense on the southern line, and the other took the defensive position in kohat. The Afghan army of 4, men met the enemy in Khyber, Ghazni and Kandahar in three ways. The British army is well-trained and well-equipped, and also has a small number of armored vehicles and combat aircraft; The Afghan army has poor training and backward equipment. Knives and swords are the main weapons. The few guns are not only old, but also lack of ammunition. The British army has an absolute advantage in military weapons. Despite this, the Afghan people fought for independence and freedom, with high morale and heroic fighting, and received strong support from the minority insurgents on the border between India and Afghanistan, which turned the passive situation around. On May 6th, Khyber Afghan forces captured the enemy Bagh fortress with three infantry battalions, and seized the favorable terrain around Landy Cotal fortress, but failed to take advantage of the emptiness of enemy forces to capture the fortress and lost the fighter plane. British reinforcements arrived immediately, and with the support of the Royal Air Force, Bagh fortress was recaptured, and the Afghan army fought and retreated. The British army also concentrated on bombing Jalalabad and Kabul, causing panic among the Afghan army and citizens. When the British army was preparing to attack Jalalabad, it was learned that the Afghan army had taken the initiative to attack in the middle and was forced to divide its troops to reinforce. Ghazni moved quickly in the direction of the Afghan army. On May 19, he entered the border town of Madun, commanding and forcing the enemy to retreat. Immediately, the path was cut into Tal at the gates, which directly threatened the enemy's stronghold in kohat and disrupted the British deployment. The Afghan army bombarded the city of Tar with artillery, but failed to capture the city due to the unfavorable coordination of artillery. After the British reinforcements arrived, the Afghan army took the initiative to withdraw from the fighting in order to preserve its strength. On the southern front, the Afghan army took the defensive, persevered tenaciously in the face of the superior enemy's attack, inflicted heavy casualties on the enemy and forced him to stop attacking. The heroic resistance of the Afghan army and the upsurge of the Indian liberation movement made the British invading army in a difficult situation and forced to give up the plan to continue fighting. At that time, the Afghan army was at a disadvantage in terms of organization, equipment and numbers, while the British and Indian troops were unable to carry out a long-term war because they had just been exhausted in the First World War. A month later, the two sides signed an armistice agreement. Since then, Oman Nura Khan's delegation has negotiated with the British government for two years and three months, and finally won. In October 1921, the British government was forced to recognize Afghanistan's complete political and diplomatic independence. At the same time, the Oman Nura regime also signed treaties of friendship and alliance with the Soviet Union, Turkey, Iran and other countries, which consolidated the international status of the Afghan regime.