The Sino-Indian War was a military conflict between the People's Republic of China (PRC) and the Republic of India that occurred in 1962. The main cause of the war was a long-standing border dispute between the two countries, specifically over the Himalayan border regions of Aksai Chin and Arunachal Pradesh.

In the years leading up to the war, India had claimed sovereignty over these regions, while China maintained that they were a part of Chinese territory. Tensions between the two countries had been simmering for a while, but they boiled over in 1962 when Chinese troops suddenly crossed the border into India and began to advance into Indian-claimed territory.

The war began on October 20, 1962, with a surprise Chinese attack on Indian positions in the Ladakh region. The Chinese forces quickly overran Indian positions and advanced deep into Indian-claimed territory. Indian forces were caught off guard and were unable to mount an effective defense.

The fighting was primarily limited to the mountainous border regions and was characterized by small unit actions, with both sides using traditional infantry and artillery tactics. The Chinese forces had a clear advantage in terms of equipment, training and logistics, and were able to quickly overrun the Indian positions.

The war ended on November 21, 1962, with a ceasefire. By this time, the Chinese had captured a large portion of Indian-claimed territory, including the Aksai Chin region, which they continue to hold to this day. India suffered a heavy defeat, and the war had a profound impact on the nation's psyche and foreign policy.