Operation Bison is the codename of the assault and capture of Zoji La, Dras and Kargil district in Ladakh by the Indian Army during the Indo-Pakistani War of 1947.
Zoji La had been seized by Pakistani raiders in 1948 in their campaign to capture Ladakh. The pass was captured by Indian forces on 1 November in a daring assault, which achieved success primarily due to the surprise use of armour, then the highest altitude at which armour had operated in combat in the world.
Initially, an unsuccessful attack was launched by 77 Parachute Brigade (Brig Atal) to capture Zoji La. Operation Duck, the earlier name for this assault, was renamed as Operation Bison by Lt Gen Cariappa, the Western Army commander. M5 Stuart light tanks of 7 Cavalry were moved in dismantled conditions through Srinagar and winched across bridges while two field companies of the Madras Sappers converted the mule track from Baltal up the Zoji La to Gumri into a jeep track. The surprise attack on 1 November by the brigade with armour supported by two regiments of 25 pounders and a regiment of 3.7 inch guns, saw the Pakistanis being surprised. The pass was forced and the raider column pushed back to Matayan and later Dras. The brigade linked up on 24 November at Kargil with Indian troops advancing from Leh while the Pakistanis eventually withdrew northwards toward Skardu.