At that time, the Indo-Pak border was open. People still crossed back and forth and the currency of each country was used in towns on either side.
In 1965, Pakistan launched "Operation Gibraltar". 40,000 Pakistani troops and irregulars, disguised as locals, entered Jammu and Kashmir to provoke a rebellion among the population. There was a great stir amongst the Muslim population due to the mysterious disappearance of a holy relic - a hair from the beard of the Prophet Mohammed, from Kashmir's Hazratbal shrine. Then President General Ayub Khan and Foreign Minister ZA Bhutto (Benazir's father) believed that they could seize most of Kashmir and force India to the negotiating table where the seizure would be legitimized.
India counter-attacked across the LOC and captured most of the infiltrators. Pakistan then launched "Operation Grand Slam" and attacked J+K with Patton tanks (which they had promised the US they would not use against India). They attempted to seize Akhnoor Bridge and cutoff the supply lines to an Indian infantry division and threaten Jammu. The Patton tanks were far superior to India's AMX tanks and Pakistan believed they would crush the Indian response.
India stopped the advance and proceeded to attack across the international border in the Punjab, an escalation of the conflict that the Pakistanis did not think likely. This was now full scale war.
After the 1965 Indo-Pak war, things rapidly went downhill for Pakistan. South Korea became an economic power while Pakistan remained mired in the third world.
60 captured Patton tanks were displayed at Bhikiwind village, nicknamed Patton Nagar.
Indian children still play there.
Many Pakistani commentators write with longing for the time when the South Koreans (and many others) regularly came to them for advice on industrial policy.