The Indo-Pakistani War of 1965 was a culmination of skirmishes that took place between April 1965 and September 1965 between India and Pakistan. This conflict became known as the Second Kashmir War fought by India and Pakistan over the disputed region of Kashmir, the first having been fought in 1947. The war began following Pakistan's Operation Gibraltar, which was designed to infiltrate forces into Jammu and Kashmir to precipitate an insurgency against rule by India. The five-week war caused thousands of casualties on both sides. It ended in a United Nations (UN) mandated ceasefire and the subsequent issuance of the Tashkent Declaration.
The Pakistani invasion of India in 1965, similar to that of 1947, was a well thought out diabolical plan consistent with Pakistan's anti-India and annex-Kashmir policies pursued since its formation. The objectives and modus operandi were the same. Pakistan-trained infiltrators supported by its regular army soldiers were pushed into Indian territory with the same purpose of sabotage, disruption and distribution of arms among the locals to start a guerrilla uprising. The prevailing conditions which encouraged Pakistan to undertake the misadventure were in fact, construed as ideal by Pakistan. The death in May 1964 of Pandit Jawaharlal Nehru and the coming to power of the late Lal Bahadur Shastri as Nehru's successor were treated by Pakistan as an encouragement to complete its unfinished war of 1947. Shastri was considered as a weakling and India was perceived as being deeply pre-occupied with its internal crises. Therefore, Pakistan assumed that India would not be able to react effectively to the situation. Pakistan believed that the population of Kashmir was generally discontented with Indian rule and that a resistance movement could be ignited by a few infiltrating saboteurs. Pakistan attempted to ignite the resistance movement by means of a covert infiltration, codenamed Operation Gibraltar. The Pakistani infiltrators were soon discovered, however, their presence reported by local Kashmiris, and the operation ended in a complete failure Pakistan claimed to have been concerned by attempts of India to absorb Kashmir - a state claimed by Pakistan as "disputed", into the Indian Union. The basis for this claim was the application of Articles 356 and 357 of the Indian Constitution that allow the President of India to declare President's Rule in the State.
On August 15, 1965, Indian forces crossed the border and launched an attack on the territory of Kashmir administered by Pakistan. Pakistani reports cite this attack as unprovoked while assessments from India and neutral sources cite this as a response to Pakistan's infiltration into Jammu and Kashmir as part of Operation Gibraltar. Initially, the Indian Army met with considerable success, capturing three important mountain positions after a prolonged artillery barrage. By the end of August, however, both sides had relative progress; Pakistan had made progress in areas such as Tithwal, Uri and Punch and India had captured the Haji Pir Pass, eight kilometers into Pakistan-occupied Kashmir. On September 1, 1965, Pakistan launched a counterattack, called Operation Grand Slam, with the objective to capture the vital town of Akhnoor in Jammu, which would sever communications and cut off supply routes to Indian troops. Attacking with an overwhelming ratio of troops and technically superior tanks, Pakistan made gains against Indian forces, who were caught unprepared and suffered heavy losses. India responded by calling in its air force to blunt the Pakistani attack. The next day, Pakistan retaliated, its air force attacked Indian forces and air bases in both Kashmir and Punjab. India's decision to open up the theater of attack into Pakistani Punjab forced the Pakistani army to relocate troops engaged in the operation to defend Punjab. Operation Grand Slam therefore failed, as the Pakistan Army was unable to capture Akhnoor; it became one of the turning points in the war when India decided to relieve pressure on its troops in Kashmir by attacking Pakistan further south.
India crossed the International Border on the Western front on September 6, marking an official beginning of the war. On September 6, the 15th Infantry Division of the Indian Army, under World War II veteran Major General Prasad, battled a massive counterattack by Pakistan near the west bank of the Ichogil Canal (BRB Canal), which was a de facto border of India and Pakistan. These developments brought the Indian Army within the range of Lahore International Airport. On the days following September 9, both nations' premiere formations were routed in unequal battles. India's 1st Armored Division, labeled the "pride of the Indian Army", launched an offensive towards Sialkot. The Division divided itself into two prongs, was forced back by the Pakistani 6th armoured division at Chawinda and was forced to withdraw after suffering heavy losses of nearly 100 tanks. The Pakistanis followed up their success by launching Operation Windup, which forced the Indians back farther. Similarly, Pakistan's pride, the 1st Armored Division, pushed an offensive towards Khemkaran, with the intent to capture Amritsar (a major city in Punjab, India) and the bridge on River Beas to Jalandhar. The Pakistani 1st Armored Division never made it past Khem Karan, however, and by the end of September 10 lay disintegrated by the defences of the Indian 4th Mountain Division at what is now known as the Battle of Asal Uttar.
The war saw the Indian Air Force and the Pakistani Air Force engaged in full scale combat for the first time since independence. Though the two forces had previously faced off in the First Kashmir War during the late 1940s, that engagement was limited in scale compared to the 1965 conflict. Despite the qualitative and numerical superiority of Pakistani armour, Pakistan was outfought on the battlefield by India, which made progress into the Lahore-Sialkot sector, whilst halting Pakistan's counteroffensive on Amritsar; they were sometimes employed in a faulty manner, such as charging prepared defenses during the defeat of Pakistan's 1st Armored Division at Assal Uttar.
The Pakistan Army launched a number of covert operations to infiltrate and sabotage Indian airbases.On September 7, 1965, the Special Services Group (SSG) commandos were parachuted into enemy territory. The daring attempt proved to be an "unmitigated disaster".Only 22 commandos returned to Pakistan as planned, 93 were taken prisoner (including one of the Commanders of the operations, Major Khalid Butt), and 20 were killed in encounters with the army, police or civilians. The reason for the failure of the commando mission is attributed to the failure to provide maps, proper briefings and adequate planning or preparation. India responded to the covert activity by announcing rewards for captured Pakistani spies or paratroopers.
The war was heading for a stalemate, with both nations holding territory of the other. The Indian army suffered 3,000 battlefield deaths, while Pakistan suffered 3,800. The Indian army was in possession of 710 mile² (1,840 km²) of Pakistani territory and the Pakistan army held 210 mile² (545 km²) of Indian territory. The territory occupied by India was mainly in the fertile Sialkot, Lahore and Kashmir sectors, while Pakistani land gains were primarily south in deserts opposite to Sindh and in Chumb sector near Kashmir in north. Pakistan's army had been able to withstand Indian pressure, but a continuation of the fighting would only have led to further losses and ultimate defeat for Pakistan. Most Pakistanis, schooled in the belief of their own martial prowess, refused to accept the possibility of their country's military defeat by "Hindu India" and were, instead, quick to blame their failure to attain their military aims on what they considered to be the ineptitude of Ayub Khan and his government. On September 22, the United Nations Security Council unanimously passed a resolution that called for an unconditional ceasefire from both nations. Peace had been achieved on September 23 by the intervention of the great powers who pushed the two nations to a cease fire for fears the conflict could escalate and draw in other powers. The war ended the following day.The Soviet Union, led by Premier Alexey Kosygin, hosted ceasefire negotiations in Tashkent (now in Uzbekistan), where Indian Prime Minister Lal Bahadur Shastri and Pakistani President Ayub Khan signed the Tashkent Agreement, agreeing to withdraw to pre-August lines no later than February 25, 1966.
India continued to increase its defense spending after the war. The Indian Armed Forces, which was already undergoing rapid expansions, made improvements in command and control to address some shortcomings. Partly as a result of the inefficient information gathering preceding the war, India established the Research and Analysis Wing for external espionage and intelligence Moreover, Pakistan had lost more ground than it had gained during the war and, more importantly, failed to achieve its goal of occupying Kashmir; this result has been viewed by many impartial observers as a defeat for Pakistan. Many high ranking Pakistani officials and military experts later criticized the faulty planning of Operation Gibraltar that ultimately led to the war. The Tashkent declaration was also criticized in Pakistan, though few citizens realised the gravity of the situation that existed at the end of the war. Political leaders were also criticized.