The 4th South African Infantry Battalion (4SAI) is based in Middleburg, Mpumalanga.
It was originally converted to a Mechanised Infantry Battalion in 1987 for the latter stages of the Angolan War campaign, although in recent years has reverted to a Motorised Infantry Battalion.
4SAI was briefly known as the 62nd Mechanised Battalion for Operation Moduler and then changed to simply Battle Group Charlie after its operational call sign in Operations Moduler, Hooper and Packer.
