He became major in 1787, visited England in 1789, and purchased a lieutenant-colonelcy in 1790, returning to India in the following year. He held a brigade command in the war against Tippoo, and served under Cornwallis in the Seringapatam operations of 1792, being promoted colonel in 1795. Baird served also at the Cape of Good Hope as a brigadier-general, and he returned to India as a major-general in 1798. In the last war against Tippoo in 1799 Baird was appointed to the senior brigade command in the army. At the successful assault of Seringapatam Baird led the storming party, and was soon a master of the stronghold in which he had long been a prisoner.
He had been disappointed that the command of the large contingent of the nizam was given to Colonel Arthur Wellesley; and when after the capture of the fortress the same officer obtained the governorship, Baird judged himself to have been treated with injustice and disrespect. He afterwards received the thanks of parliament and of the British East India Company for his gallant bearing on that important day, and a pension was offered to him by the Company, which he declined, apparently from the hope of receiving the order of the Bath from the government. General Baird commanded the Indian army which was sent in 1801 to co-operate with Abercromby in the expulsion of the French from Egypt. Wellesley was appointed second in command, but owing to ill-health did not accompany the expedition. Baird landed at Kosseir, conducted his army across the desert to Kena on the Nile, and then to Cairo. He arrived before Alexandria in time for the final operations.
On his return to India in 1802, he was employed against Sindhia, but being irritated at another appointment given to Wellesley he relinquished his command and returned to Europe. In 1804 he was knighted, and in 1805—1806, being by now a lieutenant-general, he commanded the expedition against the Cape of Good Hope with complete success, capturing Cape Town and forcing the Dutch general Janssens to surrender. But here again his usual ill luck attended him. Commodore Sir Home Popham persuaded Sir David to lend him troops for an expedition against Buenos Aires; the successive failures of operations against this place involved the recall of Baird, though on his return home he was quickly re-employed as a divisional general in the Copenhagen expedition of 1807. During the bombardment of Copenhagen, Baird was wounded.
Shortly after his return, he was sent out to the Peninsular War in command of a considerable force which was sent to Spain to cooperate with Sir John Moore, to whom he was appointed second in command. It was Baird's misfortune that he was junior by a few days both to Moore and to Lord Cavan, under whom he had served at Alexandria, and thus never had an opportunity of a chief command in the field. At the battle of Corunna he succeeded to the supreme command after Moore's fall, but shortly afterwards his left arm was shattered, and the command passed to Sir John Hope. He again obtained the thanks of parliament for his gallant services, and was made a K.B. and a baronet. Sir David married Miss Campbell-Preston, a Perthshire heiress, in 1810. He was not employed again in the field, and personal and political enmities caused him to be neglected and repeatedly passed over. He was not given the full rank of general until 1814, and his governorship of Kinsale was given five years later. In 1820 he was appointed commander-in-chief in Ireland, but the command was soon reduced, and he resigned in 1822. He died on the 18th of August 1829.
See Theodore Hook's Life of Sir David Baird.