received some backing from the United States, military aid was soon withdrawn. By the middle of 1958, the group had been forced into a low-intensity guerrilla warfare based in the jungles of Sumatra. Despite continued defeats, Sjafruddin still refused to attempt a compromise with the Jakarta government. On the first anniversary of PRRI, he gave a speech attacking Sukarno for working with communists, and urging a federal state. In a last-ditch political attempt, the Masyumi leadership and the dissident military leaders announced the "United Republic of Indonesia" at Bonjol on 8 February 1960. In the proclamation, Sjafruddin was named president of the Republic, but little else beyond the state's constitution was announced. The declaration did not amount to much, and the Indonesian government continued to pressure PRRI, capturing rebel-held towns in Sumatra's highlands. By July, the rebel stronghold at Koto Tinggi where Sjafruddin and the other Masyumi/PRRI leaders resided had been captured, forcing them to flee and disabling their capacity to lead the rebellion. Army Chief of Staff Abdul Haris Nasution, in order to further split the government of PRRI, announced an amnesty program for rebelling troops in late 1960. In April and May 1961, they began surrendering to the government, although PRRI still controlled much of the rural regions of West Sumatra. Sjafruddin and Natsir appointed Maludin Simbolon to represent PRRI in negotiating with the central government, but the military leaders opted to surrender separately. Between June and 17 August, nearly all of PRRI's troops and military commanders surrendered, leaving the civilian leaders few options. Sjafruddin himself had been negotiating with Nasution since July, and alongside Assaat and Burhanuddin Harahap he submitted to military authorities near Padangsidempuan on 25 August. He did so after advising his own remaining followers to "cease hostilities" in a radio broadcast on 17 August. Sjafruddin also surrendered PRRI's assets in form of of gold bullion. This left only Natsir and Colonel Dahlan Djambek as PRRI's remaining leadership, and after Djambek's death on 13 September, Natsir too surrendered on 25 September, ending PRRI's rebellion. Sjafruddin was initially not imprisoned, due to a 1961 declaration of amnesty for PRRI members by Sukarno, and for a time he stayed around Medan. However, in March 1962, he was brought to Jakarta, and then held as a prisoner in Kedu for two years before being transferred to a military prison in Jakarta in 1964. After the fall of Sukarno