Pakistan, objectively speaking, attempted aggression after its birth in 1947 four times and got something out of them two times. It faced aggression from India in 1971 which resulted in its losing half of its country out of which an independent country of Bangladesh was born.
Firstly it was against the princely state of Jammu and Kashmir (J & K) in 1948 which had yet to make up its mind on whether to join Pakistan or India when Pakistani tribal forces attacked it. Thereafter J & K joined India in return for Indian armed forces saving the rest of J & K from the tribal invaders. Finally the Prime Minister of India took the issue to the UN which called for a ceasefire and resulted in Pakistan having control over one-third of J & K and India having control over two-thirds of it and having the whole of J & K as a part of India on paper.
The second instance was in 1965 when Pakistan launched a campaign to capture parts of a region called Rann of Kutch in the West of India and South-East of Pakistan. This region was disputed between Pakistan and India and finally Pakistan managed to occupy large swathes of it which were unguarded by India owing to it being an inhospitable salt desert. Then emboldened Pakistan launched a third campaign immediately against the rest of J & K not under its control. This caused Indian retaliation in the form of its occupying large parts of Pakistani-occupied J & K and parts of Sindh and Punjab regions of Pakistan. Finally a ceasefire was proposed by some foreign countries which both Pakistan and India accepted. In the end Pakistan and India returned eachother whatever territory they had occupied from the other with Pakistan being allowed to keep 10% out of whatever of Rann of Kutch it claimed. However its aims of wresting J & K from India were not met in 1965 and it faced a defeat there.
In the opinion of GlobalSecurity.org on the 1965 Indo-Pak war , "The losses were relatively heavy — on the Pakistani side, twenty aircraft, 200 tanks, and 3,800 troops. Pakistan's army had been able to withstand Indian pressure, but a continuation of the fighting would only have led to further losses and ultimate defeat for Pakistan."
The fourth instance of Pakistan committing aggression against India was in 1999 when its regular army personnel dressed in civilian outfits occupied strategic peaks on the Indian controlled part of J & K in the Kargil region there during the winter. This brought about an overwhelming Indian retaliation in the summer when India discovered the occupation. India retook peak after peak from the Pakistani soldiers without crossing into Pakistani held part of J & K (India maintained the sanctity of the 1948 war ceasefire line in J & K called the LoC against all odds in 1999). Finally the Prime Minister of Pakistan visited US which proposed a ceasefire. India thereafter ceased its fire while the occupying Pakistani forces evacuated themselves out of the Indian part of J & K. Thus in 1999 Pakistan failed to wrest Indian controlled part of J & K from India by force yet again.
A note about what ATL_ROX has posted. It is filled for the most part with things conjured out of thin air except the great tactics shown by the Pakistani Air Force in the 1965 war and the discipline and professionalism of the Pakistani military. While no one will dispute the above two things, all the rest of it written in his/her post is completely inaccurate and every neutral source in the world will attest to it. If he/she insists on otherwise then neutral proof should be provided to attest to the same.
Regarding the claim that Pakistan is filled with warrior-minded people and India is/has been militarily weak, the mere military history between India and Pakistan where in each of Pakistan's almost half a dozen encounters with the Indian military, all it managed was a patch of salt-desert which if it had been important for India it wouldn't have been given away so easily (refer to the rout by India of Pakistani soldiers from the very strategic peaks of Kargil in 1999) versus India splitting Pakistan into half in 1971 speaks for itself about which country, India or Pakistan, can claim military superiority over the other in the history of their existence.
Pakistani military victories weren't so much victories as a victory against the hapless independent state of J & K half of which Pakistan managed to conquer in 1948 until India came to its rescue and therefter took the matter to the UN naively without liberating the whole of J & K from Pakistani occupation.
As for the rest, winning against this and that unit of the adversary here and there in the numerous wars fought by Pakistan can't be claimed to be military victories. Pakistan may have got the better of its adversary in a handful of engagements in the numerous wars it fought but it has never won a war despite such blatantly and outrageously untruthful *stories* that most Pakistanis are brought up to believe in. Infact such beliefs of theirs is very annoying and amusing for the rest of the world.