What would the Royal Sussex Regiment have been doing in South Africa between 1900-1902?

What was the Royal Sussex Regiment?

The Royal Sussex Regiment was a line infantry regiment of the British Army that was in existence from 1881 to 1966. The regiment was formed in 1881 as part of the Childers Reforms by the amalgamation of the 35th (Royal Sussex) Regiment of Foot and the 107th Regiment of Foot (Bengal Light Infantry).