ISLAMABAD, Pakistan — In a surprise move, Lt. Gen. Raheel Sharif was appointed the chief of the Pakistani Army on Wednesday, ending months of speculation about who would succeed Gen. Ashfaq Parvez Kayani, who will retire on Friday.

Of the three main contenders for the post — the most powerful military position in the country — General Sharif was the least senior in terms of service. The second most senior of the candidates, Lt. Gen. Rashad Mahmood, was named chairman of the Joint Chiefs of Staff Committee, according to a statement from the office of Prime Minister Nawaz Sharif. Lt. Gen. Haroon Aslam, the most senior, was bypassed.

Both of the new appointees will be promoted to become four-star generals.

According to the country’s constitution, the prime minister makes the appointments of the service chiefs. Choosing the army chief had been considered one of the most important and delicate decisions facing Mr. Sharif. The military has ruled Pakistan for most of the country’s history. During Mr. Sharif’s previous tenure, his handpicked army chief, Gen. Pervez Musharraf, toppled the government in 1999. More