al-Din, these were based at the capital and 10,000 strong, most armed with rifles. The "flags" were further divided into rubs ("quarters") consisting of 800 to 1200 fighters. In turn, rubs were split into four sections, one administrative, one jihadiya, one sword- and spear-wielding infantry, and one cavalry. The jihadiya units were further split into "standards" of 100 led by officers known as ra's mi'a, and into muqaddamiyya of 25 under muqaddam. Navy The Mahdist navy emerged during the early rebellion, as the insurgents took control of boats operating on the Nile. In May 1884, the Mahdists captured the steamboats Fasher and Musselemieh, followed by the Muhammed Ali and Ismailiah. In addition, several armed steamboats which had been supposed to aid Charles Gordon's besieged force were wrecked and abandoned in 1885. At least two of these, the Bordein and Safia, were salvaged by the Mahdists. The captured steamboats were armed with light artillery pieces, and crewed by Egyptians as well as Sudanese. The Mahdist navy also used supply ships. In October 1898, parts of the Mahdist navy were sent up the White Nile to assist the expedition against Emin Pasha's forces. The Ismailiah was sunk on 17 August 1898 as it was placing naval mines on the Nile near Omdurman to block the advance of Anglo-British gunboats. One mine accidentally exploded, destroying the ship. The Safia and Tawfiqiyeh, towing barges with 2,000 to 3,000 soldiers, were sent up the Blue Nile against French forces holding Fashoda on 25 August 1898. There, the two ships attacked the fort, but the Safia broke down and was exposed to heavy fire before being towed to safety by the Tawfiqiyeh. The Tawfiqiyeh subsequently retreated to Omdurman, but encountered a large Anglo-Egyptian fleet on the way and surrendered. The Mahdist navy fought its last battle on 11 or 15 September 1898, when the Anglo-Egyptian gunboat Sultan encountered the Safia near Reng. The two ships fought a short battle, and the Safia was badly damaged before being boarded and captured. The Bordein was eventually captured when Omdurman fell to the Anglo-Egyptian forces. Uniform At the start of his insurgency, the Mahdi encouraged his followers to wear similar clothing in form of the jibba. As a result, the core army of the Mahdi and Abdallahi ibn Muhammad had a relatively regulated appearance from an early point. In contrast, other armies of supporters and allies initially did not