Short Answer- To appease the furious pakistani public.
Long answer for the inquisitive sort-
The 1965 war was inconclusive. Both sides suffered heavy losses, although the Pakistanis lost a far larger proportion of their armed forces. In the long run India would have obviously won. The Pakistanis were really low on ammunition and could not continue the war for long.
While their forces fought bravely against us by the end of the war they were operating on the ragged edge due to heavy losses . It was observed by most of the military experts in other countries that an Indian victory was certain. Thanks to the intervention of the Western powers, Pakistan was spared from the ignominy of a huge defeat.
So why does Pakistan think it won?
The Pakistanis were very confident of victory over India. They thought that they could win easily after seeing India’s lackluster performance in the 1962 war. Also a US Report suggested that Pakistan would win in the event of a India- Pak war. This emboldened the Pakistani generals to try and capture Kashmir.
Two of the most important reasons why the Pakistani Leaders called the 1965 war a success were-
‘The So Called Martial Prowess’-
The Pakistani Public was fed blatant lies about their martial superiority over the ‘weak Indians’. This was obviously a carry over from the post-1857 British ideas of ‘Martial races’. Several Pakistani subgroups were included among the list of‘Martial races’. Basically the theory suggested that some races were better soldiers than other races. The British were obviously wrong, but still the Pakistani army stubbornly believed this archaic theory till 1965.
Pakistan’s army also had the latest Patton tanks which gave it a technological edge over India’s old Centurions and Sherman tanks in 1965. This technological edge was much touted by the Pakistani Leaders to their people.
Hence the Pakistani Public was misled by their leaders into believing that their‘Martial Race’ of Soldiers would win a grand victory over the ‘Cowardly Indians’ . They also spread propaganda proclaiming that one Pakistani soldier was equal to 10 Indian soldiers.
The Public was kept in the dark throughout the war and honestly believed that they were winning. The truth was that the ‘Cowardly Indians’ laid waste to the much superior Patton Tanks of the Pakistani Military in several battles. This was mostly due to the utter incompetence of the Pakistani commanders.
Battle of Asal Uttar
When the Pakistani government agreed to a ceasefire to prevent a total defeat, the Pakistani public was very surprised that the army did not inflict a crushing defeat on India.
Till the announcement of the Tashkent talks, Pakistani propaganda kept on talking about huge Pakistani victories in the war. Hence when the decision for a ceasefire was made, the public anger was palpable.
To calm this Public anger, The Pakistani Leaders said that they were on the verge of victory and had to agree to a Ceasefire only because of the UN.
The Economic aspect-
Pakistan’s economy had seen an impressive growth spurt in the early 1960’s thanks to the brilliant decisions of it’s leaders like the president Ayub Khan. At the same time Nehru era India of the period was hampered by ineffective economic policies which were the worst of the capitalist and socialist world.
This period came to a swift end as Pakistani army Expenditure increased from 4.82% to 9.89% of the GDP during 1964-1965 putting a Immense strain on the Pakistani Economy. The public backlash was only restrained thanks to the lies of their leaders who proclaimed that Military Expenditure was necessary to beat the Indians. The public grudgingly agreed to this.
If the Pakistani Government told it’s people that it had lost badly even after spending so much of it’s resources on the military and thrashing the economy to bits, the public would have been furious. There was a very real chance of a revolution in Pakistan.
Hence, the leaders called the 1965 war, a victory. There was a huge uproar over the Tashkent declaration, because the public believed that Pakistan was winning and crushing the Indians and they wanted a total and absolute victory for Pakistan.
They were outraged with the results of the Tashkent talks and they promptly kicked Ayub Khan out of power. Ayub Khan was no saint but he was a far better leader than his successors.
Just think what would have happened if the public knew the truth. They probably would have wanted his head.
Conclusion – These are the two main reasons why the Pakistani government declared the 1965 war a victory. After the war they increased military spending to 55% of the GDP again on the same pretext .
And… as you all know, they lost, terribly. Again, the main reason was overconfidence and the belief that the defence of East Pakistan lay in West Pakistan. This pushed Pakistan’s economy even further into the ditch.
You know, after reading about these wasteful wars, I cannot help but sympathize with the ordinary Pakistani civilians and the common soldiers who were duped by their military chiefs. After all, they were betrayed by their very own generals in a most barbaric way.
I believe that it hadn’t been for these stupid conflicts, we could have prospered side by side as two great nations. Kashmir would have been a beautiful and peaceful valley rather than a land rocked by violence and unrest. We could have been two best friends.
Moreover, SAARC(South Asian Association for Regional Cooperation) which has India, Pakistan, Nepal, Sri lanka, Bhutan, Bangladesh, Maldives and Afghanistan could have been a major player in geopolitics. SAARC has immense potential, but it is all going to waste, thanks to the inane rivalry between our two great nations.