What makes the Pakistani army so powerful over the civilian government?

Military is the most powerful institution in pakistan. It is so powerful that it is known as "the state within a state" 

Since its creation in 1947, Pakistan has always kept a military force much more than what it actually needed because they were paranoid that if they do not keep a strong army the much powerful  India will attack and destroy them. (This paronoria still remains in Pakistan) So pakistanis eventually created and fed an army so big that they can't control. When pakistan was in internal turmoil barely a decade after its creation, the military establishment utilized the opportunity and created a military regime for the first time in 1958 which lasted till 1971. ISI (pakistan's intelligence agency) which is an extnsion of the Pakistani military, headed by army generals also played crucial role in this process. In 1971 after Indian armed forces separated east Pakistan from west and helped in the formation of Bangladesh, the Indian paronoria gradually resurged in pakistan, then in 1977 military again did a coup in the country under general zia. This time by hanging prime-minister bhutto. Zia regime lasted till his death in 1988. Zia created and supported right-wing terrorist groups across pakistan targeting Afghanistan and India. Right-wing became more powerful in pakistan with military support and imported Wahabi ideologies from Gulf. Civil war in the Afghanistan also created a favorable situation for them in Pakistan.  By this time military had a complete control over the political system of the country and became extremely powerful. During this time ISI became well funded and infiltrated inside every institution in the country. (USA and Saudi Arabia always supported and favored military regimes in Pakistan as it was easy to deal directly with miltary than with the messy and confused politicans) From 1988 to 1999 many elected governments formed but military establishment indirectly controlled the defence and foreign policy of Pakistan. Even ISI is accused by some for rigging those elections in favour of the military sponserd candidates.

In 1999, soon after the defeat of Pakistan in the kargil war against India, the civil-military relations hit rock bottom again. Pakistan military did a coup again this time under general musharaff and then prime-minster nawaz shereef forced to seek asylum in Saudi Arabia. The following military rule continued till 2008. 

Though officially Pakistan is a Democratic country, military sets the rules there and controls the government. In short, Pakistan made an army which is much stronger than any other institutions, so it has become easy for the army generals to dominate in the internal affairs.

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