On the 23rd of September 1823 an armed party of Burmese attacked a British guard on Shapura, an island close to the Chittagong side, killing and wounding six of the guard. Two Burmese armies, one from Manipur and another from Assam, also entered Cachar, which was under British protection, in January 1824. War with Burma was formally declared on the 5th of March 1824. On the 17th of May a Burmese force invaded Chittagong and drove a mixed sepoy and police detachment from its position at Ramu, but did not follow up its success. The British rulers in India, however, had resolved to carry the war into the enemy's country; an armament, under Commodore Charles Grant and Sir Archibald Campbell, entered the Rangoon river, and anchored off the town on the 10th of May 1824. After a feeble resistance the place, then little more than a large stockaded village, was surrendered, and the troops were landed. The place was entirely deserted by its inhabitants, the provisions were carried off or destroyed, and the invading force took possession of a complete solitude. On the 28th of May Sir A. Campbell ordered an attack on some of the nearest posts, which were all carried after a steadily weakening defence.
Another attack was made on the 10th of June on the stockades at the village of Kemmendine. Some of these were battered by artillery from the war vessels in the river, and the shot and shells had such effect on the Burmese that they evacuated them, after a very unequal resistance. It soon, however, became apparent that the expedition had been undertaken with very imperfect knowledge of the country, and without adequate provision. The devastation of the country, which was part of the defensive system of the Burmese, was carried out with unrelenting rigour, and the invaders were soon reduced to great difficulties. The health of the men declined, and their ranks were fearfully thinned. The monarch of Ava sent large reinforcements to his dispirited and beaten army; and early in June an attack was commenced on the British line, but proved unsuccessful. On the 8th the British assaulted. The enemy were beaten at all points; and their strongest stockaded works, battered to pieces by a powerful artillery, were in general abandoned.
With the exception of an attack by the prince of Tharrawaddy in the end of August, the enemy allowed the British to remain unmolested during the months of July and August. This interval was employed by Sir A. Campbell in subduing the Burmese provinces of Tavoy and Mergui, and the whole coast of Tenasserim. This was an important conquest, as the country was salubrious and afforded convalescent stations to the sick, who were now so numerous in the British army that there were scarcely 3000 soldiers fit for duty. An expedition was about this time sent against the old Portuguese fort and factory of Syriam, at the mouth of the Pegu river, which was taken; and in October the province of Martaban was reduced under the authority of the British.
The rainy season terminated about the end of October; and the court of Ava, alarmed by the discomfiture of its armies, recalled the veteran legions which were employed in Arakan, under their renowned leader Maha Bandula. Bandula hastened by forced marches to the defence of his country; and by the end of November an army of 60,000 men had surrounded the British position at Rangoon and Kemmendine, for the defence of which Sir Archibald Campbell had only 5000 efficient troops. The enemy in great force made repeated attacks on Kemmendine without success, and on the 7th of December Bandula was defeated in a counter attack made by Sir A. Campbell. The fugitives retired to a strong position on the river, which they again entrenched; and here they were attacked by the British on the 15th, and driven in complete confusion from the field.
Sir Archibald Campbell now resolved to advance on Prome, about 100 m. higher up the Irrawaddy river. He moved with his force on the 13th of February 1825 in two divisions, one proceeding by land, and the other, under General Willoughby Cotton, destined for the reduction of Danubyu, being embarked on the flotilla. Taking the command of the land force, he continued his advance till the 11th of March, when intelligence reached him of the failure of the attack upon Danubyu. He instantly commenced a retrograde march; on the 27th he effected a junction with General Cotton's force, and on the 2nd of April entered the entrenchments at Danubyu without resistance, Bandula having been killed by the explosion of a bomb. The English general entered Prome on the 25th, and remained there during the rainy season. On the 17th of September an armistice was concluded for one month. In the course of the summer General Joseph Morrison had conquered the province of Arakan; in the north the Burmese were expelled from Assam; and the British had made some progress in Cachar, though their advance was finally impeded by the thick forests and jungle.
The armistice having expired on the 3rd of November, the army of Ava, amounting to 60,000 men, advanced in three divisions against the British position at Prome, which was defended by 3000 Europeans and 2000 native troops. But the British still triumphed, and after several actions, in which the Burmese were the assailants and were partially successful, Sir A. Campbell, on the 1st of December, attacked the different divisions of their army, and successively drove them from all their positions, and dispersed them in every direction. The Burmese retired on Malun, along the course of the Irrawaddy, where they occupied, with 10,000 or 12,000 men, a series of strongly fortified heights and a formidable stockade. On the 26th they sent a flag of truce to the British camp; and negotiations having commenced, peace was proposed to them on the following conditions: - (1) The cession of Arakan, together with the provinces of Mergui, Tavoy and Ye; (2) the renunciation by the Burmese sovereign of all claims upon Assam and the contiguous petty states; (3) the Company to be paid a crore of rupees as an indemnification for the expenses of the war; (4) residents from each court to be allowed, with an escort of fifty men; while it was also stipulated that British ships should no longer be obliged to unship their rudders and land their guns as formerly in the Burmese ports.
This treaty was agreed to and signed, but the ratification of the king was still wanting; and it was soon apparent that the Burmese had no intention to sign it, but were preparing to renew the contest. On the 19th of January, accordingly, Sir A. Campbell attacked and carried the enemy's position at Malun. Another offer of peace was here made by the Burmese, but it was found to be insincere; and the fugitive army made at the ancient city of Pagan a final stand in defence of the capital. They were attacked and overthrown on the 9th of February 1826; and the invading force being now within four days' march of Ava, Dr Price, an American missionary, who with other Europeans had been thrown into prison when the war commenced, was sent to the British camp with the treaty (known as the treaty of Yandaboo) ratified, the prisoners of war released, and an instalment of 25 lakhs of rupees. The war was thus brought to a successful termination, and the British army evacuated the country.