The siege of Muscat occurred in 1650, when an Omani army under Sultan bin Saif attacked the Portuguese fort of Muscat and captured the town from the Portuguese, ending the long Portuguese occupation of Muscat.

By 1648, all of the Portuguese possessions in Oman had fallen to the Yarubids, and they were only left with Muscat, Muttrah and Khasab. On August 16, 1648, the Omani leader Sa'id bin Khalifa besieged Muscat. The place managed to hold out until September 11, when the Portuguese asked for a peace treaty. As the ammunition of the garrison was all used, the Omanis imposed their own conditions: the fortresses of Qurayyat and Dibba should be demolished, the Omani fortress at Muttrah should be recognized, merchants in the highlands would not pay tribute to the Portuguese, and the walls of Muscat should be demolished.

The Portuguese refused these terms and continued the siege until they heard of the surrender of Mocala Hills to the Omanis without any resistance while a plague struck the garrison. Finally, on October 31, the Portuguese would finally make a peace treaty, with the following conditions: the fortresses of Qurayyat, Dibba, and Muttrah would be demolished along with the Omani fort of the latter; Muttrah would be neutral; Omani vessels could navigate outwards without reserve except in Portuguese lands, where they would need a passport to enter; Omanis would pay no customs; and all Omani fortresses in Muscat would be demolished.

When this news reached Lisbon on March 16, 1650, the Portuguese king was dismayed at this peace treat and ordered Julião de Noronha, the captain of Muscat, to be arrested and sent to Goa. During this year, Nasir bin Murshid died in April and was succeeded by Sultan bin Saif. The first thing the new Imam did was prepare for the siege of Muscat.

The Portuguese garrison of Muscat consisted of European men and Indian mercenaries from Goa; these troops took defensive positions outside the fort in hills and mountains nearby. The Portuguese fortresses São João and Capitão were the headquarters for leadership, supplies, and cannons; they were both heavily fortified. The Portuguese and Indian infantry were distributed in the Sa'ali and Mocala mountains. One of their mountain fortresses was a block shape that controlled the route to Muscat, which they blocked with iron chains.

Imam Sultan had been preparing his army in Tuwa al-Rowla, a place near Muttrah, and he took it as his base. He then moved his fighting forces into Sayh Harmal and there ordered an attack on a group of hills called Bir al-Rawiya; however, they were met with heavy fire from the Portuguese, which threw them into disarray and withdrew a next assault, which was met with a similar result. Imam Sultan then ordered the attack to stop; the Portuguese used this and hastily retreated to their two fortresses; the Omanis swiftly chased them to the fort and besieged them; there, the Omanis challenged the garrison into a duel, but none called the answer, according to the Omani narrative. An Indian man called Narottam, an officer working in the castle storehouse, the Portuguese captain, a certain Pereira, asked his daughter for marriage, Naruttam wasn't satisfied with this and secretly contacted the Imam who ordered him to spoil the gunpowder storage to which he did, while the Portuguese soldiers were busy celebrating Christmas, the Imam, after the dawn prayer, launched his attack, climbed up the walls and began putting a sword on the Portuguese and Indians, one of the fiercest resistance was led by a Portuguese officer named Cabreta but he was forced to retreat to the shops where he was killed by the Omanis, the whole garrison was nearly wiped out and few managed to escape, the Omanis then went to Muttrah but surrendered to them.

Portuguese sources state that a number of inhabitants—around 700—arrived at Diu on January 18, 1650, the Omanis suffered between 4,000 and 5,000 deaths in the siege, while the Portuguese garrison was only 60 or 70 alive and later converted to Islam and integrated into the society. The commander of the fort surrendered.

The capture of Muscat marked the end of Portuguese rule in Oman and in the Persian Gulf and had only a small base of Khasab until 1655. On March 16, 1652, a Portuguese fleet was dispatched from Goa to recapture Muscat; however, the expedition ended in failure, and thus Muscat was secured. The victory gave rise to the Omani navy, which would culminate in the capture of Mombasa in 1698.

• Falih Handhal, Arab and Portuguese in History from 711 to 1720.[1]
• Frederick Charles Danvers, The Portuguese In India, Vol. 2.[2]
• Aysha Ali al-Sayyar, The Yarubid State of Oman and East Africa between 1624 and 1741.
• Alexander Hamilton, A New Account Of The East-indies Vol.1.[3]

• Portuguese Oman
• Capture of Sohar
• Capture of Julfar
• Siege of Mombasa (1696–1698)