Sepoys (probably from Pers. sipahi, a soldier), the native soldiers of the British army in India. The practice of employing the natives as troops originated with the French about the middle of the 18th century, and in 1748 the East India company organized a small body of sepoys at Madras, which had increased to 14 battalions, numbering 10,000 men, at the time of the battle of Plassey. Two of the battalions took part in the expedition under Clive, who at once began to form a similar native army in Bengal, which as early as 1765 contained 19,000 troops. A sepoy force was also raised in Bombay, which consisted of about 3,500 men in 1772; and in 1773, when the office of governor general was established, the estimated strength of the East India company's native army was 45,000 men. This entire military establishment was reorganized in 1796 on a basis which remained essentially unchanged till 1861. A native regiment was about 1,100 strong in Bengal, and 900 in Madras and Bombay; there were about 120 native non-commissioned officers, 20 native commissioned officers, and theoretically 25 European officers, but in fact only 12 or 15. The highest rank to which a native could attain was that of subahdar or captain; native lieutenants were known as jemadars, and sergeants as havildars.

The sepoys were volunteer troops. Those of the Bengal army were mainly high-caste Hindoos, but in the armies of Madras and Bombay the aristocratic element was not so prominent. According to Kaye, the Bengal sepoy was to the outward eye the finest soldier, tallest, best formed, and of the noblest presence; but he was less docile and serviceable than the sepoy of the southern and western armies. Notwithstanding occasional local mutinies and murderous outbreaks on the part of the native soldiery, their discipline, fidelity, and good service in the field, extending through so many years, inspired an extraordinary and almost universal confidence in their loyalty, which existed throughout India up to the beginning of the great sepoy revolt in 1857. (See India.) When it began, the East India company's army consisted of about 300,000 men, all sepoys with the exception of 40,000. The mutiny was almost wholly confined to the Bengal army; in Madras but a single regiment was disaffected, and in Bombay none at all; while the native forces from the Punjaub assisted in repressing the rebellion. Upon the subsequent transfer of the army to the crown, a reorganization became necessary.

This was effected in 1861, by a reduction of its numbers one half, the abolition of promotion by seniority, and the permanent appointment of seven effective officers to each regiment. The troops are nominally on the footing of irregulars. There are 137 battalions of infantry, 40 regiments of cavalry, and a few batteries of artillery. The number of men in 1873 was 128,447, of whom 103,343 were infantry.