Operation Grand Slam was a key military operation of the Indo-Pakistani War of 1965. It refers to a plan drawn up by the Pakistan Army in May 1965 that consisted of an attack on the vital Akhnoor Bridge in Jammu and Kashmir, India. The bridge was not only the lifeline of an entire infantry division of the Indian Army, but could also be used to threaten the city of Jammu, an important logistical point for Indian forces. The operation saw initial success, but was aborted when the Indian Army opened a new front in the Pakistani province of Punjab in order to relieve pressure in Kashmir. This forced Pakistan to abandon Grand Slam and fight in Punjab, thus the operation ended in failure and the stated objectives were not achieved.
Planning
The Operation Grand Slam was designed as a twin of the Operation Gibraltar, both of which were meant to jeopardise India's control of Kashmir and bring it to the negotiating table without risking a general war across the international border. The idea for Grand Slam came from President Ayub Khan. When he reviewed the plans for Gibraltar in May 1965, he pointed to Akhnur on the map and called it a "jugular" for India. By seizing Akhnur, India's overland supply route to Kashmir would be cut off.
Ayub Khan was mistaken. India's supply route to Kashmir did not pass through Akhnur. (The National Highway 1A passed through Udhampur and Ramban, not Akhnur.) General Akhtar Malik, who was in charge of both Gibraltar and Grand Slam, however understood the President's demand for a "jugular". He developed secret plans to proceed to Jammu after taking Akhnur, where he could cut off the highway. These plans were not revealed to the President, who would have apprehended the possibility of a general war.
Also mired in confusion were the conditions under which Grand Slam was to be launched. According to some sources Grand Slam was to be launched only after Gibraltar had succeeded. A failure of Gibraltar should have necessitated a rethink. According to others, Grand Slam itself was needed in order to "encash" Gibraltar. Neither Gibraltar nor Grand Slam had the full support of the Army Headquarters.
In addition to these confusions, there was also a technical issue. In order to avoid the possibility of a general war, Pakistan needed to make the operation appear to be a "localised conflict" in Kashmir. This meant launching its attack across the cease-fire line in Kashmir. But the operational plans for Grand Slam required the Pakistani forces to cross a "small section" of the border between Pakistani Punjab and Kashmir, which India regarded as an international border. In the event, it made no difference to India which border the Pakistani forces crossed.
Indian weaknesses
Even though Akhnur was not the "jugular" that President Ayub Khan imagined, it was still a key choke point. It had the only bridge across the Chenab River in this area, on which ran the supply route to the western districts of Rajouri and Poonch. The bridge was capable of carrying only light tanks. It had not been strengthened over the years, despite warnings from various local commanders. In addition, the cease-fire line was defended only lightly, as per the UN-mediated cease-fire agreement at the end of the First Kashmir War. It would be quickly overrun in the event of a full scale invasion.
At the time of the opening attack of Operation Grand Slam, the Chhamb Jaurian sector was defended on the Indian side by the 191st (Independent) Infantry Brigade, comprising three battalions, and supported by a squadron of 20 Lancers , which was equipped with AMX-13 light tanks.
Decision to launch
The Operation Gibraltar went badly. The plan was to infiltrate thousands of troops into Jammu and Kashmir, India in the guise of 'mujahideen', who would carry out sabotage to demoralise the Indian forces and incite the local population to revolt. But the local population did not rise, the infiltrators were quickly identified and the Indian Army began to hunt them down. In addition, the Indian Army moved across the cease-fire line to cut off the Pakistani infiltration routes and captured the Haji Pir pass (in (POJK) Pakistan Occupied Jammu and Kashmir) and some heights in the Kargil sector.