India and Pakistan have always been involved in some conflict or other basically because of the differences between the major religions that govern these countries, i.e. Hinduism and Islam. The formation of Pakistan itself in 1947 is based on acute conflict between Hindus and Muslims, a difference that had been sustained ever since.
Immediately after the partition when Pakistan was formed, a wave of hostility and violence swept both the countries resulting in one of the worst carnages in the history of mankind. This was followed by two major wars, one war in 1965 and the other war in 1971.
This war is also known as the Second Kashmir War. The trigger for this war was the infiltration of Pakistani troupes in India with the aim of recapturing Kashmir. This region is divided between the two countries since 1947 and it has remained a bone of contention ever since. Pakistan had called this maneuver ‘Operation Gibraltar’. In August 1965 the troupes of both countries crosses the cease-fire borders and captured cities in the opposite territories.
The war mostly fought by the infantry and air forces escalated out of control by September 1965 when China threatened to intervene. USA and Great Britain prevented this from happening by appealing to UN and as a result of their intervention India and Pakistan withdrew their forces to the territory demarcated before the war commenced.
The then Prime Ministers of both countries, Mr Lal Bahadur Shashti (India) and Mr Ayub Khan met subsequently in Tashkent (USSR) in January 1966 to sign an agreement which binds both the countries to peace and observance of cease-fire terms and conditions.
Though this war is commonly known as Indo-Pakistan war, it is actually the Bangladesh Liberation War. This war started internally in Pakistan on 3rd December 1971 and ended with a major defeat to Pakistan on 16th December 1971 when Bangladesh gains its Independence.
The conflict was triggered by the unrest between the East and West Pakistan when the former demanded more freedom and autonomy. The East Pakistan constituted mostly of Bengalis. USA actively supported Pakistan in this war while India with support from France and United Kingdom backed the East Pakistani Bengalis in their fight for freedom. The coup de grace came when USSR joined India through a treaty signed on August 9th, 1972 which assured their friendship and cooperation at all levels between the two countries.
India launched a counter attack on Pakistan following their air assault on Indian Territory. The Indian Army was able to occupy the entire eastern half, which later declared itself as an Independent country, i.e. Bangladesh on December 6th, 1971. The internal conflict as well as the casualty of the war coupled with the fact that some 10 millions Bengalis fled the country to India (due the war) crippled Pakistan to a very large extent. For a while it was believed that Pakistan might not survive this defeat.
However, in 1972 India and Pakistan entered a new treaty called the Shimla Accord under the persuasion from the UN and peace once again prevailed. As a sign of goodwill, India returned a large part of the occupied territory – some 13 thousand kilometers square as a gesture of goodwill. In 1974 Pakistan recognized Bangladesh as an independent entity and country.