[2] However, Letsie, the paramount chief and first son of Moshoeshoe, and many of the Sotho ruling establishment, rallied to support the Cape forces, and the rebellion was put down after several months of arduous fighting.
Morosi was the son of Mokuane, a Baphuthi man, and Maidi (daughter of chief Tshosane) at Marunyeng (the present day Thoteng) in Mohale's hoek district.
[5] In the 1820s, during the course of the Mfecane, Mohale a brother of the paramount chief of Basutoland Moshoeshoe I, decided to raid the Baphuthi in order to steal their cattle.
In early 1829, Morosi went on a successful joint expedition with Moshoeshoe I against the Thembu of Ngubengcuka who lived below the Drakensberg, carrying away large herds of cattle.
[10] During the Battle of Berea, when Sir George Cathcart brought a force into Basutoland in 1852, Morosi was largely responsible for defeating him.
There were no hostilities until June 1865, when President Johannes Brand sent an ultimatum to Moshoeshoe after some Free State burghers had been imprisoned and ill-treated by the latter, and then proclaimed war.
On 20 June 1865, before daylight 2000 warriors under Poshuli and Morosi crossed the Caledon near its junction with Wilgeboom Spruit, and commenced to ravage the district before them.
From the farm adjoining the commonage of Smithfield they laid waste a broad belt of country for a distance of thirty miles towards Bloemfontein.
[24] In recognition of Morosi's military assistance and successes, most recently in the war with the Orange Free State, Moshoeshoe granted him lands in the southwestern corner of Basutoland.
[25] Morosi and the approximately 1,500 Baphuthi men, along with their women and children took refuge on a mountain, where he requested a week to respond to the Cape Government's offer of safe return if he gave up the offenders.
[26] The mountain has sheer drops on three sides and the fourth consists of a 30° slope, which he reinforced with a series of strong walls, 8–12 feet (2.4–3.7 m) high, impervious to artillery, with loopholes for guns.
[26] There Morosi took refuge with around 300 Baphuthi soldiers and sufficient ammunition, food and cattle to resist a long siege, beginning 24 March, until he was finally overrun on 20 November.
[28] A mortar and ammunition was sent up from King William's Town and fixed about 400 metres (1,300 ft) from the first wall behind a rapidly built, stone bastion.
[36][2] In the storming of his stronghold, Morosi's sons were also killed, with the exception of Doda, who escaped with around 120 men by jumping into the Orange River.
[41] The conflict between Morosi and the Cape forces was one of the defining events of the exercise of authority in Phuthiland and Basutoland overall, which relied on the use of firearms and control of economic production.
[42][43] The Cape Government of Prime Minister Gordon Sprigg, in eventually overcoming Morosi, was assisted by Basuto soldiers armed with guns.
[45] Morosi's rebellion therefore played a significant role in maintaining the identity of the territory and the existence of Lesotho as a nation state today.