The Indo-Pakistani War of 1965 or the Second Kashmir War was a culmination of skirmishes that took place between April 1965 and September 1965 between Pakistan and India. The conflict began following Pakistan's Operation Gibraltar, which was designed to infiltrate forces into Jammu and Kashmir to precipitate an insurgency against Indian rule. India retaliated by launching a full-scale military attack on West Pakistan. The seventeen-day war caused thousands of casualties on both sides and witnessed the largest engagement of armored vehicles and the largest tank battle since World War II. Hostilities between the two countries ended after a ceasefire was declared through UNSC Resolution 211 following a diplomatic intervention by the Soviet Union and the United States, and the subsequent issuance of the Tashkent Declaration. Much of the war was fought by the countries' land forces in Kashmir and along the border between India and Pakistan. This war saw the largest amassing of troops in Kashmir since the Partition of India in 1947, a number that was overshadowed only during the 2001–2002 military standoff between India and Pakistan.