The Indian Army Corps of Engineers has a long history dating back to the mid-18th century. The earliest existing subunit of the Corps (18 Field Company) dates back to 1777, while the Corps officially recognises its birth as 1780, when the senior-most group of the Corps, the Madras Sappers, were raised. The Corps consists of three groups of combat engineers, namely the Madras Sappers, the Bengal Sappers, and the Bombay Sappers. A group is roughly analogous to a regiment of Indian infantry, each group consisting of a number of engineer regiments. The engineer regiment is the basic combat-engineer unit, analogous to an infantry battalion.