One of Jolo's most able sultans, Muhammad Alimuddin, (variously spelled Alimud Din, Al Mudin, Alimuddin, Alim ud Din) is also commonly referred to as Don Fernando de Alimuddin I inasmuch as he was a Catholic.
The young Alimuddin was brought up in the school of his father and sent to Batavia (now Djakarta) to complete his education. There he became proficient in Arabic and Malayan and gained mastery of the Koran.
He was such a wise and enlightened ruler that he was said to have attained among his subjects "an authority almost supreme." To him also was accorded the title of "Chief of Pandita" on account of his erudite and precise explanations of the Koran.
One of the earliest events in the reign of Alimuddin was his ratification of the Treaty of 1737. He was represented in Manila by Datu Mohammad Ismael and Datu Ja'far, who both signed the document. The treaty, drawn in January, 1737 by Governor-General Fernando Valdes y Tamon, contained five articles: first, the preservation of permanent peace between the two states; second, the provision for alliance and mutual aid against any foreign foe; third, free trade between the two states; fourth, responsibility of each state for all infractions of the peace; and fifth, provision for the exchange of captives and return of all church images and ornaments.
Alimudin I was a man of peace and a reformer, besides he kept his part of the treaty faithfully and piracy was actually obliterated during the whole period he held the reigns of government. He revised the Sulu code of laws and its system of justice. He caused parts of the Koran and several texts on law and religion to be translated into the local language. He strongly urged his people to observe their religion faithfully. He wanted all panditas to learn Arabic and initiated the drafting of an Arabic-Sulu vocabulary as a preliminary step into making Arabic the official language of the state. He coined money, organized a small army, and tried to establish a navy. His name is foremost in the memory of the Sulus, partly because of his able administration and partly on account of the fact that he was the ancestor of all the present principal datus of the Sulus.
On July 12, 1744, King Philip V of Spain sent him a letter requesting permission for the Jesuits missionaries to propagate Christianity in Sulu. When his panditas learned that he had given his consent, they raised fierce opposition. A party was formed under the leadership of Prince Bantilan. Alimuddin's brother, for the purpose of, expelling the missionaries and deposing Alimuddin. Hostilities increased and civil war became imminent.
In an effort at assassination, Bantilan thrust a spear at Alimuddin and inflicted a severe wound on his side or thigh. During the disturbances and the confusion that followed, it became too dangerous for the missionaries to remain at Jolo. Overpowered, disheartened, and grieved, Alimuddin left Jolo with his family and numerous escorts and went to Zamboanga to seek the aid of Spain against Bantilan who had taken over the government without opposition. Bantilan did not send away the Jesuits but he gave them no opportunity to accomplish their mission. As sultan, he took the name M'i'zzudin, Defender of the Faith.
Alimuddin landed in Cavite on 2 January 1749. In Manila, Governor Juan de Arechederra gave him royal reception, one befitting a Prince of high rank. The Sultan was publicly received in the Hall of the Audiencia. But instead of immediately getting down to the main purpose of his visit, he told Arechederra - to that man's great joy - that he wanted to be instructed in the Christian faith preparatory to receiving baptism. The governor-bishop refused to believe this, anxious though he was to see a Christian on the throne of Jolo. He appointed a board of experts to examine Alimuddin. After the examination, all but the two Jesuits on the board recommended that he be baptized.
The governor sent him to his own diocese and baptized him in Paniqui, then a part of Pangasinan, on the 29th of April 1750. He was baptized Don Fernando de Alimuddin I, and became the first Christian Sultan of Jolo. His son Israel and his daughter Fatimah were likewise converted to Christianity and both were given a Spanish education in Manila.
In July, 1750, Governor Francisco de Obando, Aredhederra's successor, sent an expedition to Jolo to restore Alimuddin to his sultanate. On May 19, 1751 Alimuddin and his retinue were sent on board the Spanish friagate San Fernando and were conveyed by a squadron composed of seven vessels under the command of Field Marshall Antonio Ramon de Abad. The San Fernando docked at Iloilo where Alimuddin changed boats. Meeting with contrary winds the sultan's party was carried off course to Dapitan. From there they set sail again for Zamboanga.
Before Alimuddin left Manila, he addressed a letter to the Sultan of Mindanao, at the instance of the Spanish Governor-General. The original was written by him in Sulu. A version in Spanish was dictated to him and he signed both. These documents reached the governor of Zamboanga, but he had the original in Sulu retranslated and found out that it did not at all agree with the Spanish version. This letter was pronounced treasonable.
As a result, the year 1753 was said to have been the bloodiest in the history of the Moro wars. Priests were slain, whole towns destroyed, and thousands of captives carried into slavery. Alimuddin petitioned the governor to allow Princess Fatimah to go to Jolo for the purpose of arranging a peace with Bantilan. The princess succeeded and Bantilan agreed to stop his raids and return Christian prisoners and church property. He declared his wish and true desire for peace. He expressed deep regret for Alimuddin and for the hostility and gave strong assurances regarding the reestablishment of peace with Spain. He also gave assurances that the sultan was not a traitor at all but a man of good intentions who was simply unable to carry out some of his plans and promises because of the determined resistance of many of the principal datus. But Alimuddin was not released.
In 1754, Pedro Manuel de Arandia succeded Obando as governor general. The new governor treated Alimuddin with more kindness and consideration, gave him a monthly pension and allowed his family and friends to return to Jolo.