Chief of General Staff, shortly abbreviated as CGS, is the most coveted position within the Pakistan Army. Although four-star Chief of Army Staff (COAS) is the nominal head of the land forces, CGS is the operational and intelligence lead of the institution. It is headed by a three-star lieutenant general.
Traditionally, the selection for COAS or Chairman Joint Chiefs of Staff Committee (CJCSC) has a preference for Chief of General Staff posting. The last 13 four-star army generals had eight officers who did a tenure as CGS. Out of five who didn't, Pervez Musharraf and Ashfaq Parvez Kayani stayed as Director General of Military Operation (DGMO) and Ehsan ul Haq stayed as Director General of Military Intelligence (DGMI), all two-star postings under the CGS.
The current CGS is Lt Gen Bilal Akbar since 11 December 2016.
The CGS heads the General Staff Branch of Army General Headquarters. He is also assisted by a Vice Chief of General Staff (VCGS) and Deputy Chief of General Staff), both two-star major generals. The critical directorates of Military Operations and Military Intelligence (headed by DGMO and DGMI respectively) also come under his purview.
Historically, the CGS post, in addition to Commander X Corps, Rawalpindi, had political significance when the army chief wanted to overthrow political leadership. The 1999 Pakistani coup d'état, which brought General Pervez Musharraf to power had active involvement of Lt Gen Muhammad Aziz Khan, then CGS and Lt Gen Mahmud Ahmed, commander X Corps Rawalpindi.
Therefore, the army chief essentially positions most trusted aides for these two postings before making a routine reshuffle. General Ziauddin Butt, who was nominated by Prime Minister Nawaz Sharif after retiring Pervez Musharraf, passed his first orders to appoint Lt Gen Muhammad Akram as CGS and Lt Gen Salim Haider as Commander Rawalpindi Corps. But before this order could be conveyed to the rest of the army, Aziz and Mahmud took steps to reverse the order by overthrowing the government and thus essentially starting the 1999 coup.