By November 1947 Auchinleck, Supreme Commander based in New Delhi, being convinced that Indian Cabinet was seeking to destroy and undo Pakistan by economic and military means, was forced to resign. As the build-up of Indian forces in Jammu and Kashmir continued, Pakistan Army units were being hurriedly organized and equipped without any base for manufacture of ammunition, signal stores, equipment or vehicles. Simultaneously, Pakistan National Guards were raised from ex-servicemen and other volunteers along border areas to provide a second line of defence. By February 1948 Indian build up in Jammu and Kashmir reached five brigades plus, under two full-fledged division Headquarters. Our 101 Brigade, commanded by Brigadier Akbar Khan was rushed into the critical front to forestall and halt the Indian offensive along Uri-Muzaffarabad axis. In April 1948, Commander-in-Chief Pakistan Army appreciating the threats in the north along Muzaffarabad-Kohala axis, and in the south along Bhimber-Mirpur-Poonch axis further reinforced the front with elements of 7 Division to halt the Indian offensive at Chakothi. Reinforcements were rushed overnight to Tithwal sector to defend Muzaffarabad front 9(F) Division was also moved to reinforce 7 Division in Tithwal, Uri and Bagh sectors. 7 Division was thereafter moved to the southern front. In May Pakistan informed the United Nations of these moves. By June, Pakistan had five brigades in Jammu and Kashmir together with Azad Kashmir forces and elements of the para-military Frontier Corps, holding twelve Indian brigades (with 4 to 5 battalions each) supported by armour, artillery and Indian Air Force. Indian summer offensive was decisively beaten and halted. Some months later, two brigades of 8 Division from Quetta further reinforced Muzaffarabad-Uri front.
On 14 August 1948 , the first anniversary of Pakistan , General Headquarters sent the following message to the Quaid-e-Azam, “Loyal and grateful greetings from the Army on the first anniversary of Independence Day. We serve and shall serve Pakistan with all our hearts and souls. Pakistan and its Creator, Zindabad.” The Quaid-e-Azam was at that time in Quetta , fighting his own battle for survival against a deadly affliction. In December, Pakistan Army planned to go on the offensive, ‘Operation Venus', with 7 Division to cut off the main supply route at Beri Pattan Bridge area, and isolate Indian forces in Nowshera-Jhangar-Poonch sector. On 14 December, in a pre-attack artillery bombardment the Beri Pattan bridge area containing ammunition, rations, petrol and supplies in a two-mile area was totally destroyed together with Indian divisional Headquarter, isolating the Indian forces in that sector. The Indian Army was taken by surprise. At midnight on 30 December, India asked for ceasefire with effect from 1 January 1949 . Pakistan accepted, as the fate of Jammu and Kashmir had been taken over by the United Nations. By early 1949 Pakistan Army had completed its formative stage. It halted the Indian offensive and prevented it from totally over-running Jammu and Kashmir , and closing up to Pakistan 's vital border areas, thus ended the war in Jammu and Kashmir . Pakistan Army continued its reorganization. An ordnance factory to produce small arms and ammunition was established at Wah. The threat from India was by no means over. In spring of 1950 and again between July and October 1951 the Indian Army concentrated on Pakistan‘s borders and transgressed into Azad Kashmir and West Pakistan territory forty eight times. The Indian Air Force violated Pakistan 's air space thirty times thus bringing the two countries very close to another all out war through India 's coercive diplomacy and interventionist strategy.
Because India came to their rescue ONLY on the condition that they become part of India - we did not want to go about fighting for foreign countries, in 1948. The ruler of Kashmir soon signed the instrument of accession and acceeded Kashmir to India, just as many other princely states had done. Once it is part of our country, there is no question of any referendum.
As for soldiers:
1) We do not have 700,000 soldiers in Kashmir, the number is far less.
2) We need a high number of soldiers there because our neighbour covetes that state, and has fought four wars with us to take that state, and we want to prevent that from happening. Also, because we know that the most likely flashpoint in any future war is going to be Kashmir.
So basically india came there to help then they annexed that area.