The 18th Regiment of Bengal Native Infantry was one of the major infantry battalions of the British East India Company, which existed from the year 1795 to 1922. It was a part of the Bengal Native Infantry under the Army of the Bengal province, before the beginning of the Great Revolt of 1857. The Bengal Army was the principal armed force of Bengal Presidency. King Edward VII acted as the Colonel-in-Chief of the battalion in the year 1904. The army unit was also incorporated as a part of the Bengal Command. The 18th Regiment of Bengal Native Infantry was also known as the 18th Infantry unit.

History of 18th Regiment of Bengal Native Infantry
The 18th Regiment of Bengal Native Infantry was raised as the Calcutta Native Militia in the year 1795 to protect the assets of the Honourable British East India Company. The army unit was re-designated many times throughout its armed service, such as, the Alipore Regiment; the 18th Bengal Native Infantry; and 18th (Alipore) Bengal Native Infantry. Eventually the battalion was re-designated as the 18th Infantry, after the Kitchener reforms of the British Indian Army.

Military Operations of 18th Regiment of Bengal Native Infantry
The 18th Infantry unit took part in various battles and military conquests. The Bengal Native Infantry regiment did not participate in the Great Revolt, also known as the Sepoy Mutiny in 1857. Several of the regiments in the Army of Bengal Presidency revolted and as a result those regiments of the Bengal Army were dissolved. Later the British Empire in India took control over the British East India Company and the three Presidency Armies, namely the Bengal Army, the Madras Army and the Bombay Army after the Government of India Act 1858 was institutionalized. The 18th Regiment of Bengal Native Infantry fought in the Third Anglo Burmese War in the year 1885 and the First World War. The unit became a part of the Derajat Brigade during the Great War and participated in army operations on the North West Frontier.

Development of 18th Regiment of Bengal Native Infantry
After the First World War, the British Government of India renumbered and restructured the Indian army. The separate single battalion infantry regiments were merged together in order to develop multi battalion regiments. The 18th Infantry unit was regrouped as the 4th Battalion 9th Jat Regiment. During the re-organisation of the British Indian Army in 1922, the unit was assigned the Regimental Centre that was situated at Bareilly. The other units of the Jat Regiment were developed from the former Bombay (2nd Multan battalion) and the Bengal (1st and 3rd battalions) regiments.

After the country earned freedom from the supremacy of the British Empire in India on 15th August 1947, the nation was divided into the Union of India and the Dominion of Pakistan through the Partition of India. The British Indian Army was divided amongst the 2 nations and the military unit was assigned to the modern Indian Army.

Designations of 18th Regiment of Bengal Native Infantry
The 18th Regiment of Bengal Native Infantry occupied various designations and titles through out its existence under the British Indian Army. The various names are mentioned below-
* Calcutta Native Militia in 1795
* The Alipore Regiment in 1859
* 18th Bengal Native Infantry in 1861
* 18th (Alipore) Bengal Native Infantry in 1864
* 18th Regiment of Bengal Native Infantry in 1885
* 18th Musulman Rajput Infantry in 1902
* 18th Infantry in 1903
* 4th Battalion 9th Jat Regiment in 1922
* Assigned to Indian Army in 1947