The Burmese king Bayinnaung conquered all of the Shan states in 1557. Although the Shan states would become a tributary to Irrawaddy valley based Burmese kingdoms from then on, the Shan Saophas retained a large degree of autonomy. Throughout the Burmese feudal era, Shan states supplied much manpower in the service of Burmese kings. Without Shan manpower, it would have been harder for the Burmans alone to achieve their victories in Lower Burma, Siam, and elsewhere. Shans were a major part of Burmese forces in the First Anglo-Burmese War of 1824-1826, and fought valiantly—a fact even the British commanders acknowledged.