After the treaty of Yandaboo 1826 (After first Anglo-Burmese War), a large number of British merchants had settled on the southern coast o f Burma and Rangoon. Tharrawady, the new king of Burma (1837-1845) refused to consider the treaty of Yandaboo. The British Residents also did not get proper treatment at the court and finally the Residency had to be withdrawn in 1840.
The British merchants often complained of ill treatment at the hands of the Governor of Rangoon. They sent a petition to Lord Dalhousie. Dalhousie was determined to maintain British prestige and dignity at all the costs and so deputed Commodore Lambert to Rangoon to negotiate the redress of grievances and demand compensation. At first the King of Burma was inclined to avoid war and removed the old Governor and appointed the new one. But when a deputation of some naval officers was refused admission, Lambert adopted a very provocative line of action. He captured one of the Burmese King's ships. With this incident, the Burmese did not resist and the war was declared.