The Sikh Khalsa Army, also known as Khalsaji or simply Sikh Army, was the military force of the Sikh Empire. With its roots in the Khalsa founded by Guru Gobind Singh, the army was later modernised on Franco-British principles by Maharaja Ranjit Singh. It was divided in three wings: the Fauj-i-Khas (elites), Fauj-i-Ain and Fauj-i-Be Qawaid (irregulars). Due to the lifelong efforts of the Maharaja and his European officers, it gradually became a prominent fighting force of Asia. Ranjit Singh changed and improved the training and organisation of his army. He reorganized responsibility and set performance standards in logistical efficiency in troop deployment, manoeuvre, and marksmanship. He reformed the staffing to emphasize steady fire over cavalry and guerrilla warfare, improved the equipment and methods of war. The military system of Ranjit Singh combined the best of both old and new ideas. He strengthened the infantry and the artillery. He paid the members of the standing army from treasury, instead of the Mughal method of paying an army with local feudal levies.

The Sikh Empire was a regional power based in the Punjab region of the Indian subcontinent. It existed from 1799, when Maharaja Ranjit Singh captured Lahore, to 1849, when it was defeated and conquered by the British East India Company in the Second Anglo-Sikh War. It was forged on the foundations of the Khalsa from a collection of autonomous misls. At its peak in the 19th century, the empire extended from Gilgit and Tibet in the north to the deserts of Sindh in the south and from the Khyber Pass in the west to the Sutlej in the east as far as Oudh. It was divided into four provinces: Lahore, which became the Sikh capital; Multan; Peshawar; and Kashmir from 1799 to 1849. Religiously diverse, with an estimated population of 4.5 million in 1831, it was the last major region of the Indian subcontinent to be annexed by the British Empire.